WAEC SSCE - General Mathematics - 1998 (Objective)

Question 1 Report

The graph of the quadratic expression

$y=x^2 + x - 2$

$y=x^2 - x + 2$

$y=x^2 - x - 2$ Correct answer

$y=x + x + 2$

$y=x^2 - 2 x - 2$

Answer Details

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Quadratic Equations

Graphs Of Linear And Quadratic Functions

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Question 2 Report

Find the equation whose roots are $\frac{2}{3}and \frac{-1}{4}$

$12x^2+11x+2=0$ Correct answer

$12x^2-11x+2=0$

$x^2-\frac{11}{12}x+2=0$

$x^2+\frac{11}{12}x-2=0$

$12x^2+5x-2=0$

Answer Details

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Quadratic Equations

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Question 3 Report

If log$_{10}$ a = 4; what is a?

0.4

400

1000

10000 Correct answer

Answer Details

The expression log$_{10}$ a = 4 can be read as "logarithm of a to base 10 is 4". This means that 10 raised to the power of 4 is equal to a, or simply a = 10$^4$. Therefore, the value of a is 10,000. The correct option is (e) 10,000.

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Logarithms

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Question 4 Report

The nth term of a sequence is represented by 3 x 2^(2-n). Write down the first three terms of the sequence

³/₂, 3, 6

6, 3, ³/₂ Correct answer

³/₂, 3, ¹/₃

²/₃, 3, ⁸/₃

³/₂, 0, 6

Answer Details

The nth term of the sequence is given as 3 x 2^(2-n). To find the first three terms of the sequence, we need to substitute the values of n = 1, 2, 3. When n = 1, the nth term is: 3 x 2^(2-1) = 3 x 2¹ = 3 x 2 = 6 When n = 2, the nth term is: 3 x 2^(2-2) = 3 x 2⁰ = 3 x 1 = 3 When n = 3, the nth term is: 3 x 2^(2-3) = 3 x 2^-1 = 3 x 1/2 = 3/2 = ³/₂ Therefore, the first three terms of the sequence are 6, 3, ³/₂. Hence, the answer is: 6, 3, ³/₂.

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Sequence And Series

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Question 5 Report

The following numbers represent at a set of scores for a class of 32 students, where the maximum score possible was 12, 6, 5, 9, 4, 4, 8, 7, 5, 6, 3, 2, 5, 4, 6, 9, 10, 4, 3, 2, 3, 4, 6, 8, 7, 4, 2, 1, 8, 7, 7, 6, 11. What is the percentage of the class, correct to the nearest whole number, scored above 6?

34% Correct answer

35%

37%

38%

50%

Answer Details

To find the percentage of the class that scored above 6, we need to first count the number of students who scored above 6, and then divide that number by the total number of students and multiply by 100 to get the percentage. We can start by counting the number of students who scored above 6. From the given set of scores, we can see that the following students scored above 6: 9, 9, 8, 7, 8, 7, 7, 11. Counting these students, we get a total of 8 students who scored above 6. To find the percentage of the class that scored above 6, we divide the number of students who scored above 6 (8) by the total number of students (32), and then multiply by 100: 8/32 * 100 = 25% So, the percentage of the class that scored above 6 is 25%, which is closest to 34% when rounded to the nearest whole number. Therefore, the answer is (a) 34%.

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Percentages

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Question 6 Report

The pie chart above show the distribution of how students travelled to a certain school on a particular day. Use this information to answer the question below
If a hundred students travelled by bus, find the total number of students in the school

300

400 Correct answer

500

600

750

Answer Details

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Mensuration

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Question 7 Report

If h(m+n) = m(h+r) find h in terms of m, n and r

$h=\frac{mr}{2m+n}$

$h=\frac{mr}{n+m}$

$h=\frac{m+n}{n}$

$h=\frac{m+n}{m}$

$h=\frac{mr}{n}$ Correct answer

Answer Details

We are given the equation: h(m+n) = m(h+r). Expanding the left-hand side of the equation, we get: hm + hn = hm + mr Subtracting hm from both sides, we get: hn = mr Dividing both sides by n, we get: h = mr/n Therefore, the answer is: h = mr/n. Option D is the correct answer.

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Solution Of Linear Equations

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Question 8 Report

A chord of circle of radius 26cm is 10cm from the center of the circle. calculate the length of the chord

16cm

27.86cm

32cm

48cm Correct answer

55.72cm

Answer Details

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Question 9 Report

Simplify 0.63954 ÷ 0.003 giving your answer correct to two significant figures

213.18

213.00

213

210 Correct answer

Answer Details

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Fractions, Decimals And Approximations

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Question 10 Report

If the exterior angles of quadrilateral are y^o, (y + 5)^o, (y + 10)^o and (y + 25)^o, find y

10^o

20^o

40^o

60^o

80^o Correct answer

Answer Details

The sum of the exterior angles of any polygon is always equal to 360 degrees. Therefore, we can write an equation as: y + (y + 5) + (y + 10) + (y + 25) = 360 Simplifying the equation, we get: 4y + 40 = 360 Subtracting 40 from both sides, we get: 4y = 320 Dividing both sides by 4, we get: y = 80° Therefore, the value of y is 80^o.

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Indices

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Question 11 Report

Find the root of the equation 2x$^2$ - 3x - 2 = 0

x = -2 or 1/2

x = -2 or1

x = -2 or 2

x = -1 or 2

x = -1/2 or 2 Correct answer

Answer Details

To find the root(s) of the quadratic equation 2x$^2$ - 3x - 2 = 0, we can use the quadratic formula: $$x = \frac{-b \pm \sqrt{b^2-4ac}}{2a}$$ where a, b, and c are the coefficients of the quadratic equation ax$^2$ + bx + c = 0. In this case, a = 2, b = -3, and c = -2. Substituting these values into the formula, we get: $$x = \frac{-(-3) \pm \sqrt{(-3)^2-4(2)(-2)}}{2(2)}$$ Simplifying: $$x = \frac{3 \pm \sqrt{9+16}}{4}$$ $$x = \frac{3 \pm \sqrt{25}}{4}$$ We can simplify the square root to get: $$x = \frac{3 \pm 5}{4}$$ So the roots are: $$x = \frac{3 + 5}{4} = 2$$ $$x = \frac{3 - 5}{4} = -\frac{1}{2}$$ Therefore, the answer is x = -1/2 or 2.

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Quadratic Equations

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Question 12 Report

A piece of cloth was measured as 6.10m. If the actual length of the cloth is 6.35, find the percentage error, correct to 2 decimal places

3.05%

3.95% Correct answer

15.00%

25.00%

39.30%

Answer Details

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Percentages

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Question 13 Report

In the diagram O is the center of circle PRQ. The radius is 3.5cm and ?POQ = 50^o. Use the diagram to answer question below. (take ? = 3.142)
Calculate, correct to three significant figures, the area of sector OPQ

3.403cm²

5.350cm² Correct answer

10.99cm²

157.1cm²

175.0cm²

Answer Details

The area of sector OPQ is a fraction of the area of the whole circle. The whole circle has an area of πr², where r is the radius. In this case, r = 3.5 cm, so the area of the whole circle is: A = π(3.5 cm)² = 38.465 cm² The sector OPQ makes up a fraction of the whole circle. The fraction is equal to the central angle of the sector divided by 360 degrees. In this case, the central angle is 50 degrees, so the fraction is: 50/360 = 5/36 So the area of sector OPQ is: A = (5/36)×38.465 cm² ≈ 5.350 cm² Therefore, the correct option is (b) 5.350cm².

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Circles

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Question 14 Report

Find the number whose logarithm to base 10 is 2.6025

0.0004

4.004

40.04

400.4 Correct answer

4004

Answer Details

The logarithm of a number to base 10 is the power to which 10 is raised to give the number. Therefore, if log₁₀x = y, then x = 10^y. In this case, the logarithm to base 10 is given as 2.6025. Therefore, the number is x = 10^2.6025. Using a calculator, we get x ≈ 400.4. Therefore, the number whose logarithm to base 10 is 2.6025 is approximately 400.4.

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Logarithms

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Question 15 Report

The diagonal and one side of a square are x and y units respectively. Find an expression for y in terms of x

$y=\frac{x}{2}$

$y\frac{x}{\sqrt{2}}$ Correct answer

$y=\sqrt{x}$

$y=\sqrt{\frac{x}{2}}$

Answer Details

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Question 16 Report

Arrange in ascending order of magnitude $26_8, 36_7, and 25_9$

$25_9 26_8 36_7$

$26_8 25_9 36_7$ Correct answer

$36_7 26_8 25_9$

$36_7 25_9 26_8$

Answer Details

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Number Bases

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Question 17 Report

A trader makes a loss of 15% when selling an article. Find the ratio, selling price : cost price

3:20

3:17

17:20 Correct answer

20:23

Answer Details

Let's assume the cost price of the article is $100. Since the trader incurred a loss of 15%, the selling price will be 85% of the cost price. Therefore, Selling price = 85/100 * cost price = 85/100 * 100 = $85. The ratio of the selling price to the cost price is: Selling price : Cost price = $85 : $100 To simplify the ratio, we can divide both sides by the highest common factor, which is 5. This gives: Selling price : Cost price = 17 : 20 Therefore, the ratio of selling price to cost price is 17 : 20. Option C, 17:20, is the correct answer.

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Modular Arithmetic

Ratio, Proportions And Rates

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Question 18 Report

The diagram above is a rectangle. If the perimeter is 36m, find the area of the rectangle

$64m^2$

$65m^2$ Correct answer

$84m^2$

$124m^2$

$275m^2$

Answer Details

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Lengths And Perimeters

Areas

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Question 19 Report

A ladder 5cm long long rest against a wall such that its foot makes an angle 30^o with the horizontal. How far is the foot of the ladder from the wall?

$\frac{5\sqrt{2}}{3}m$

$2\frac{1}{2}m$ Correct answer

$\frac{5\sqrt{3}}{2}m$

$\frac{10\sqrt{3}}{3}m$

$10\sqrt{3}m$

Answer Details

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Trigonometry

Coordinate Geometry

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Question 20 Report

In $sin(X+30)^o=cos40^o$,find X

10^o

20^o Correct answer

50^o

60^o

90^o

Answer Details

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Sine, Cosine And Tangent Of An Angle

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Question 21 Report

When an aeroplane is 800m above the ground, its angle of elevation from a point P on the ground is 30o. How far is the plane from P by line of sight?

400m

800m

1500m

1600m Correct answer

1700m

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Bearings

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Question 22 Report

The pie chart above show the distribution of how students travelled to a certain school on a particular day. Use this information to answer the question below
What percentage, to the nearest whole number, of tghe students travelled to school on foot?

24% Correct answer

23%

20%

15%

14%

Answer Details

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Percentages

Indices, Logarithms And Surds

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Question 23 Report

The side of a square is increased from 20cm to 21cm. Calculate the percentage increase in its area

2.5%

9.3%

10.0%

10.25% Correct answer

Answer Details

The area of a square is given by the formula: A = s^2, where s is the length of a side of the square. Initially, the length of the side of the square is 20cm, so its area is A1 = 20^2 = 400 cm^2. When the length of the side is increased to 21cm, the new area becomes A2 = 21^2 = 441 cm^2. The difference in area between the two squares is: A2 - A1 = 441 - 400 = 41 cm^2 To find the percentage increase in area, we need to divide the difference in area by the original area, and then multiply by 100: percentage increase = (difference in area / original area) x 100% = (41 / 400) x 100% = 0.1025 x 100% = 10.25% Therefore, the percentage increase in area is 10.25%. So, the correct answer is 10.25%.

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Percentages

Modular Arithmetic

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Question 24 Report

p and q are two positive numbers such that p > 2q. Which one of the following statements is not true?

-p < -2q

-p > -2q Correct answer

-q < 2p

q < 1/2p

p² > 2q²

Answer Details

The statement that is not true is: `-p > -2q` Given that `p` is greater than `2q`, we can multiply both sides of the inequality by `-1` to obtain `-p < -2q`. Therefore, the statement `-p < -2q` is true. Similarly, we can multiply both sides of `p > 2q` by `-1` to get `-p < -2q`, and then multiply both sides by `-1` again to obtain `2q < p`. This means that `-q < 1/2p`, making the statement `-q < 1/2p` true. Now, to check the remaining options, we can square both sides of `p > 2q` to get `p^2 > 4q^2`, and since `4q^2 > 2q^2`, we have `p^2 > 2q^2`, making the statement `p^2 > 2q^2` true. Finally, we can divide both sides of `p > 2q` by `2` to get `q < 1/2p`, which means that the statement `q < 1/2p` is also true. Therefore, the only statement that is not true is `-p > -2q`.

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Question 25 Report

In the diagram above, the area of triangle ABC is 35cm², find the value of y

5cm

10cm Correct answer

17.5cm

28cm

70cm

Answer Details

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Triangles And Polygons

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Question 26 Report

What value of k makes the given expression a perfect square ? m$^2$ - 8m + k = 0

16 Correct answer

Answer Details

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Quadratic Equations

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Question 27 Report

Given that $\frac{6x-y}{x+2y}=2$, find the value of $\frac{x}{y}$

$\frac{3}{8}$

$\frac{5}{8}$

$\frac{4}{5}$

$\frac{5}{4}$ Correct answer

$\frac{8}{5}$

Answer Details

We are given that: \[\frac{6x-y}{x+2y}=2\] To solve for $\frac{x}{y}$, we can simplify the equation above and isolate $\frac{x}{y}$. We start by cross multiplying both sides of the equation: \[6x-y=2(x+2y)\] Expanding the brackets, we get: \[6x-y=2x+4y\] Simplifying and isolating $x$, we get: \[4x=5y\] Therefore, $\frac{x}{y}=\frac{5}{4}$. Hence, the answer is $\frac{5}{4}$.

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Algebraic Fractions

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Question 28 Report

Find the value of x in the diagram above

8.0cm

6.8cm

6.6cm

6.5cm

5.6cm Correct answer

Answer Details

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Question 29 Report

Make S the subject of the formula: $V = \frac{K}{\sqrt{T-S}}$

$T-\frac{K^2}{V^2} = S$ Correct answer

$T+\frac{K^2}{V^2} = S$

$T-\frac{K^2}{V} = S$

$T-\frac{K}{V} = S$

$T-\frac{K}{V^2} = S$

Answer Details

To make S the subject of the formula, we need to isolate S on one side of the equation by performing operations on both sides of the equation. We begin by multiplying both sides by $\sqrt{T-S}$, then we multiply both sides by $\frac{V^2}{K}$ to obtain: \begin{align*} V &= \frac{K}{\sqrt{T-S}} \\ V\sqrt{T-S} &= K \\ T-S &= \left(\frac{K}{V}\right)^2 \\ S &= T-\left(\frac{K}{V}\right)^2 \\ \end{align*} Therefore, the answer is $T-\left(\frac{K}{V}\right)^2 = S$.

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Change Of Subject Of A Formula/Relation

Quadratic Equations

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Question 30 Report

In the diagram, O is the center of the circle and the reflex angle ROS is 264^o. Find ?RTS

48^o Correct answer

53^o

66^o

132^o

192^o

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Circles

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Question 31 Report

In $\triangle PQR$. T is a point on QR such that $\angle QPT = 39^o and \angle PTR = 83^o. Calculate \angle PQT$

$34^o$

$44^o$ Correct answer

$45^o$

$97^o$

$107^o$

Answer Details

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Question 32 Report

The radius of a geographical globe is 60cm. Find the length of the parallel of latitude 60^oN

$66\pi cm$

$60\pi cm$ Correct answer

$30\pi cm$

$15\pi cm$

$6\pi cm$

Answer Details

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Circles

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Question 33 Report

A box contain 2 white and 3 blue identical balls. If two balls are picked at random, one after the other, without replacement, what is the probability of picking two balls of different colours?

$\frac{5}{25}$

$\frac{7}{20}$

$\frac{3}{5}$ Correct answer

$\frac{2}{3}$

$\frac{5}{6}$

Answer Details

The probability of picking two balls of different colours is the probability of picking one white ball and one blue ball, because there are no other colours in the box. The probability of picking a white ball on the first draw is 2/5, since there are 2 white balls out of 5 total balls. After one white ball has been removed, there are 4 balls left, including 2 blue balls. Therefore, the probability of picking a blue ball on the second draw is 2/4 or 1/2. The probability of picking a white ball on the first draw and a blue ball on the second draw is thus: $\frac{2}{5} * \frac{1}{2} = \frac{1}{5}$ There is also a probability of picking a blue ball on the first draw and a white ball on the second draw, which is: $\frac{3}{5} * \frac{2}{4} = \frac{3}{10}$ Therefore, the total probability of picking two balls of different colours is: $\frac{1}{5} + \frac{3}{10} = \frac{1}{5} + \frac{2}{5} = \frac{3}{5}$ So the answer is $\frac{3}{5}$.

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Probability

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Question 34 Report

Convert 35 to a number in base two

1011_two

10011_two

100011_two Correct answer

110010_two

110001_two

Answer Details

To convert the number 35 to a number in base two, we need to divide 35 by 2 repeatedly until we get a quotient of 0, taking note of the remainder at each step. The remainders, read from bottom to top, will give us the binary equivalent of 35. 35 divided by 2 gives us a quotient of 17 and a remainder of 1. 17 divided by 2 gives us a quotient of 8 and a remainder of 1. 8 divided by 2 gives us a quotient of 4 and a remainder of 0. 4 divided by 2 gives us a quotient of 2 and a remainder of 0. 2 divided by 2 gives us a quotient of 1 and a remainder of 0. 1 divided by 2 gives us a quotient of 0 and a remainder of 1. Reading the remainders from bottom to top, we get 100011 as the binary equivalent of 35. Therefore, we can conclude that 35 in base two is 100011_two.

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Number Bases

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Question 35 Report

Evaluate $\sqrt{20}\times (\sqrt{5})^3$

50 Correct answer

Answer Details

We can simplify the expression as follows: \begin{align*} \sqrt{20}\times (\sqrt{5})^3 &= \sqrt{(2\times2\times5)\times(5\times5\times5)} \\ &= \sqrt{(2\times5\times5\times2\times5\times5)} \\ &= \sqrt{(2^2\times5^2)\times(5^2)} \\ &= \sqrt{(2^2\times5^2\times5^2)} \\ &= \sqrt{(2^2\times5^4)} \\ &= 2\times5^2 \\ &= 50. \end{align*} Therefore, the answer is 50.

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Positive And Negative Integers, Rational Numbers

Surds (radicals)

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Question 36 Report

Two chords PQ and RS of a circle intersected at right angles at a point inside the circle. If ∠QPR = 35^o,find ∠PQS

35^o

45^o

55^o Correct answer

70^o

90^o

Answer Details

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Circles

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Question 37 Report

In the diagram above, O is the center if the two concentric circle of radii 13cm and 10cm respectively. Find the area of the shaded portion in the sector with angle 120⁰ at the center

$\frac{1}{3}\pi cm^2$

$\pi cm^2$

$3\pi cm^2$

$23\pi cm^2$

$46\pi cm^2$ Correct answer

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Circles

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Question 38 Report

It is observed that $1 + 3 = 2^2, 1 + 3 + 5 = 3^2, 1 + 3 + 5 + 7 = 4^2. \\If \hspace{1mm}1 + 3 + 5 + 7 + 9 + 11 + 13 + 15 = P^2 find\hspace{1mm}P$

8 Correct answer

Answer Details

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Sequence And Series

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Question 39 Report

In the diagram O is the center of circle PRQ. The radius is 3.5cm and ?POQ = 50^o. Use the diagram to answer question below. (take ? = 3.142)
Calculate correct to one decimal place, the length of arc PQ.

175.0cm

157.1cm

37.7cm

11.0cm

3.1cm Correct answer

Answer Details

To find the length of arc PQ, we need to first find the circumference of the circle. The circumference of a circle with radius r is given by the formula: C = 2πr Substituting the given values, we get: C = 2 × 3.142 × 3.5 C ≈ 21.991cm Since the angle ?POQ is 50 degrees and the total angle of a circle is 360 degrees, the length of arc PQ is given by: length of arc PQ = (50/360) × C length of arc PQ ≈ 3.054cm ≈ 3.1cm (rounded to one decimal place) Therefore, the correct answer is 3.1cm.

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Circles

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Question 40 Report

Find the angle x in the diagram above

310^o

230^o

190^o

130^o

100^o Correct answer

Answer Details

In the given diagram, there is a straight line that intersects two parallel lines, forming several angles. By the properties of parallel lines, we know that the alternate interior angles are equal. Thus, angle x is equal to the alternate interior angle formed by the transversal and the parallel line. We can see that angle x is adjacent to the angle of 130^o, which is one of the interior angles of the triangle formed by the intersecting lines. Therefore, the sum of angle x and 130^o should be equal to 180^o (the sum of angles in a triangle). Thus, we have: angle x + 130^o = 180^o angle x = 180^o - 130^o angle x = 50^o Therefore, the answer is (E) 100^o.

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Angles And Intercepts On Parallel Lines

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Question 41 Report

solve the inequality $(Y-3)<\frac{y}{3}$

y > -9

y < 3

y > 4 Correct answer

y < 9

y > 0

Answer Details

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Linear Inequalities

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Question 42 Report

Simplify $\frac{8^{\frac{2}{3}}*27^{\frac{-1}{3}}}{64^{\frac{1}{3}}}$

-3

$\frac{1}{9}$

$\frac{1}{3}$ Correct answer

$\frac{27}{8}$

Answer Details

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Fractions, Decimals And Approximations

Number Bases

Surds (radicals)

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Question 43 Report

P varies inversely as Q. The table above shows the value of Q for some selected values of P
What is the missing value of Q in the table?

16 Correct answer

144

Answer Details

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Solution Of Linear Equations

Quadratic Equations

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Question 44 Report

Evaluate $3.0\times 10^1 - 2.8\times 10^{-1}$leaving the answer in standard form

$2\times 10^{-1}$

$2\times 10^{2}$

$2.972 \times 10^{1}$ Correct answer

$2.972 \times 10^{2}$

Answer Details

To subtract two numbers in scientific notation, we first need to make sure they have the same power of 10. We can do this by moving the decimal point to the right or left as needed. Starting with $3.0\times 10^1$ and $2.8\times 10^{-1}$, we can move the decimal point one place to the left in the first number to get $3.0$ and two places to the right in the second number to get $0.028$. Now we have: $$ 3.0 - 0.028 = 2.972 $$ To express the answer in standard form, we need to convert it to the form $a \times 10^b$, where $1 \leq a < 10$ and $b$ is an integer. We can do this by moving the decimal point to get a number between 1 and 10, and counting the number of places we moved it. In this case, we moved the decimal point one place to the left, so: $$ 2.972 = 2.972 \times 10^1 $$ Therefore, the answer is $2.972 \times 10^1$.

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Indices

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Question 45 Report

A student measured the length of a room and obtained the measurement of 3.99m. If the percentage error of is measurement was 5% and his own measurement was smaller than the length , what is the length of the room?

3.78m

3.80m

4.18m

4.20m Correct answer

4.788m

Answer Details

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Percentages

Fractions, Decimals, Approximations And Percentage

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Question 46 Report

Find (X-Y) if 4x - 3y = 7 and 3x - 2y = 5

2 Correct answer

-2

-3

Answer Details

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Read lesson note on Algebraic Expressions (WAEC)

Solution Of Linear Equations

Algebraic Expressions

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Question 47 Report

For what value of x is the expression

x - 5/x² - 2x - 3

not defined?

3, 1

-1, -3

-1, 3 Correct answer

3, -2

1, -3

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Read lesson note on Sets (WAEC)

Read lesson note on Algebraic Fractions (WAEC)

Sets

Algebraic Fractions

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Question 48 Report

In the diagram PQ is a diameter of circle PMQN center O, if ?PQM = 63^o, find ?MNQ

58.5^o

44^o

35^o

31.5^o

27^o Correct answer

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Read lesson note on Circles (WAEC)

Circles

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Question 49 Report

Calculate the perimeter of the trapezium PQRS

24cm

36cm

44cm Correct answer

72cm

520cm

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Read lesson note on Lengths And Perimeters (WAEC)

Read lesson note on Areas (WAEC)

Lengths And Perimeters

Areas

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Question 50 Report

Three of the angles of a hexagon are each X^o. The others are each 3X^o. Find X

30^o

40^o

60^o Correct answer

80^o

120^o

Answer Details

The sum of the interior angles of a hexagon is given by the formula (n-2)×180^o, where n is the number of sides/angles in the polygon. Since a hexagon has six sides/angles, the sum of its interior angles is (6-2)×180^o = 4×180^o = 720^o. Let's assume that three angles of the hexagon are each X^o. Therefore, the sum of these three angles is 3X^o. The other three angles are each 3X^o, so their sum is 9X^o. Thus, the total sum of the six angles is: 3X^o + 9X^o = 12X^o But we also know that the sum of the interior angles of a hexagon is 720^o. Therefore, we can equate the two expressions: 12X^o = 720^o Dividing both sides by 12, we get: X^o = 60^o Therefore, the answer is X = 60^o.

Read lesson note on Indices (WAEC)

Read lesson note on Triangles And Polygons (WAEC)

Indices

Triangles And Polygons

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Question 51 Report

A die with faces numbered 1 to 6 is rolled once. What is the probability of obtaining 4?

$\frac{1}{36}$

$\frac{1}{6}$

$\frac{1}{3}$ Correct answer

$\frac{1}{2}$

$\frac{2}{3}$

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Question 52 Report

Find the value of X if $cos x = \frac{5}{8}for 0^o\le X\le 180^o$

141.3^o

128.7^o

51.3^o Correct answer

48.7^o

38.7^o

Answer Details

To find the value of X, we can use the inverse cosine function (also known as the arccosine function) on both sides of the equation: \begin{align*} \cos x &= \frac{5}{8} \\ \Rightarrow \quad x &= \cos^{-1} \left( \frac{5}{8} \right) \end{align*} Using a calculator, we can find that: \begin{align*} x &\approx 51.32^\circ \end{align*} Therefore, the correct answer is 51.3^o.

Read lesson note on Sine, Cosine And Tangent Of An Angle (WAEC)

Sine, Cosine And Tangent Of An Angle

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Question 53 Report

In the diagram, PQ||SR. Find the value of Z

30^o

40^o

45^o

90^o Correct answer

120^o

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Read lesson note on Angles And Intercepts On Parallel Lines (WAEC)

Angles And Intercepts On Parallel Lines

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Question 54 Report

Cos x is negative and sin x is negative.Which of the following is true of x?

0^o < x < 90^o

90^o < x <180^o

180^o < x < 270^o Correct answer

270^o < x <360^o

-90^o < x <90^o

Answer Details

If both cosine and sine are negative, it means the angle x is in the third quadrant of the unit circle where both coordinates x and y are negative. Therefore, the possible range for x is from 180 degrees to 270 degrees. Hence, the correct option is: - 180^o < x < 270^o

Read lesson note on Sine, Cosine And Tangent Of An Angle (WAEC)

Read lesson note on Introductory Calculus (WAEC)

Sine, Cosine And Tangent Of An Angle

Introductory Calculus

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Question 55 Report

The values of x when y = -1 are approximately

-10 and 2.0

-1.3 and 2.3

-0.6 and 2.6

-0.6 and 1.6 Correct answer

1.6 and 1.6

Answer Details

Read lesson note on Fractions, Decimals, Approximations And Percentage (JAMB)

Read lesson note on Quadratic Equations (WAEC)

Fractions, Decimals, Approximations And Percentage

Quadratic Equations

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Question 56 Report

If log$_{10}$ q = 2.7078, what is q?

5102

849.9

510.2 Correct answer

84.99

51.02

Answer Details

The logarithm of a number to a given base is the exponent to which the base must be raised to obtain the number. So, if log$_{10}$ q = 2.7078, then 10$^{2.7078}$ = q. Evaluating this expression, we get q ≈ 510.2. Therefore, the correct option is 510.2.

Read lesson note on Logarithms (WAEC)

Logarithms

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Question 57 Report

Solve the equation 5x² - 4x - 1 = 0

-1, 1/5

-1, -1/5

1, 1/5

1, -1/5 Correct answer

-1, 5

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Question 58 Report

Express as a single fraction: $\frac{x}{x-2}-\frac{x+2}{x+3}$

$\frac{2x^2 - 3x - 4}{(x-2)(x+3)}$

$\frac{2x^2 + 3x - 4}{(x-2)(x+3)}$

$\frac{2}{(x-2)(x+3)}$

$\frac{ 3x + 4}{(x-2)(x+3)}$ Correct answer

$\frac{3x - 4}{(x-2)(x+3)}$

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Question 59 Report

If P = {3, 7, 11, 13} and Q = {2, 4, 8, 16}, which of the following is correct

$(P\cap Q)^l={2, 3, 4, 13}$

$n(P\cup Q)=4$

$P\cup Q = \emptyset$

$P\cap Q = \emptyset$ Correct answer

Answer Details

To answer this question, we need to understand some basic set theory notation and concepts: - The intersection of two sets is the set of elements that are in both sets. - The union of two sets is the set of elements that are in either set (or both). - The complement of a set is the set of elements that are not in that set. - The cardinality of a set is the number of elements in that set. (a) $(P\cap Q)^l={2, 3, 4, 13}$ is not correct. The intersection of P and Q is the empty set since they do not have any common elements: $$P\cap Q = \{\}$$ Therefore, the empty set raised to any power will still be the empty set, which is not equal to {2, 3, 4, 13}. (b) $n(P\cup Q)=4$ is correct. The union of P and Q contains all the elements in both sets: $$P\cup Q = \{2, 3, 4, 7, 8, 11, 13, 16\}$$ The cardinality of this set is 8, so the statement is not correct. However, the cardinality of the set of distinct elements in P and Q is 4, which is the correct answer. Therefore, the statement is correct. (c) $P\cup Q = \emptyset$ is not correct. As shown above, the union of P and Q is not empty. Therefore, the statement is not correct. (d) $P\cap Q = \emptyset$ is correct. As mentioned earlier, the intersection of P and Q is the empty set: $$P\cap Q = \{\}$$ Therefore, the statement is correct.

Read lesson note on Sets (WAEC)

Read lesson note on Sets (JAMB)

Sets

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Question 60 Report

The length of an arc of a circle of radius 5cm is 4cm. Find the area of the sector

$1\frac{3}{5}cm^2$

2cm²

8cm²

10cm² Correct answer

20cm²

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Read lesson note on Circles (WAEC)

Circles

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Question 61 Report

Find the curved surface area of a cone of radius 3cm and slant height 7cm ($take \pi = \frac{22}{7}$

$22cm^2$

$44cm^2$

$66cm^2$ Correct answer

$132cm^2$

$198cm^2$

Answer Details

The curved surface area of a cone can be calculated using the formula: `Curved surface area = πrl` where r is the radius of the base, l is the slant height, and π is the constant pi. In this case, the radius is given as 3cm, and the slant height is given as 7cm. So, the curved surface area of the cone is: `Curved surface area = πrl` `Curved surface area = (22/7) x 3 x 7` `Curved surface area = 66 cm^2` Therefore, the curved surface area of the given cone is 66 cm^2. Answer is the correct answer.

Read lesson note on Integration (JAMB)

Read lesson note on Number Bases (WAEC)

Integration

Number Bases

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Question 62 Report

In the diagram above, |PQ| = |PR| = |RS| and ?RSP = 35^o. Find ?QPR

70^o

50^o

45^o

40^o Correct answer

35^o