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Ajụjụ 1 Ripọtì
A solid sphere of radius 4cm has a mass of 64kg. What will be the mass of a shell of the same metal whose internal and external radii are 2cm and 3cm respectively?
Akọwa Nkọwa
1√3(12)2
= 4√3
= √3√3
= 4√3√3
m = 64kg, V = 4πr33
= 4π(4)33
= 256π3
x 10-6m3
density(P) = MassVolume
= 64256π3×10−6
= 64×3×10−6256
= 34×10−6
m = PV = 34π×10−6
x 43
π
[32 - 22] x 10-6
34×10−6
x 43
x 5 x 10-6
= 5kg
Ajụjụ 3 Ripọtì
John gives one-third of his money to Janet who has ₦105.00. He then finds that his money is reduced to one-fourth of what Janet now has. Find how much money john has at first
Akọwa Nkọwa
Let x be John's money, Janet already had ₦105, 13
of x was given to Janet
Janet now has 132
x + 105 = x+3153
John's money left = 23
x
= 14(x+315)3
= 23
24x = 3x + 945
∴ x = 45
Ajụjụ 4 Ripọtì
The number of goals scored by a football team in 20 matches is shown below:
No. of goals012345No. of matches357310
What are the values of the mean and the mode respectively?
Akọwa Nkọwa
xffx03015527143412414500
∑f
= 20
∑fx
= 35
Mean = ∑fx∑f
= 3520
= 74
= 1.75
Mode = 2
= 1.75, 2
Ajụjụ 5 Ripọtì
Akọwa Nkọwa
Simple Space: (1, 2, 3, 4, 5, 6, 7, 8, 9, 10 = 10)
Prime: (2, 3, 5, 7)
multiples of 3: (3, 6, 9)
Prime or multiples of 3: (2, 3, 5, 6, 7, 9 = 6)
Probability = 610
= 35
Ajụjụ 6 Ripọtì
List all integers satisfying the inequality -2 ≤
2 x -6 < 4
Akọwa Nkọwa
-2 ≤
2x - 6 < 4 = 2x - 6 < 4
= 2x < 10
= x < 5
2x ≥
-2 + 6 ≥
= x ≥
2
∴ 2 ≤
x < 5 [2, 3, 4]
Ajụjụ 7 Ripọtì
Find x if log9x = 1.5
Ajụjụ 8 Ripọtì
Find the values of p for which the equation x2 - (p - 2)x + 2p + 1 = 0
Akọwa Nkọwa
Equal roots implies b2 - 4ac = 0
a = 1b = - (p - 2), c = 2p + 1
[-(p - 2)]2 - 4 x 1 x (2p + 1) = 0
p2 - 4p + 4 - 4(2p + 1) = 0
p2 - 4p = 4 - 8p - 4 = 0
p2 - 12p = 0
p(p - 12) = 0
p = 0 or 12
Ajụjụ 9 Ripọtì
If three numbers P, Q, R are in ratio 6 : 4 : 5, find the value of 3p−q4q+r
Akọwa Nkọwa
P : Q : r = 6 : 4 : 5
5 = 6 + 4 + 5
= 15
P = 615
, q = 415
, r = 515
= 13
To find 3p−q4q+r
3p - q = 3 x 615
- 415
1815
- 415
= 1415
∴ 4q + r = 4 x 415
+ 515
1615
= 1615
+ 515
= 2115
1415
x 1521
= 1421
= 23
Ajụjụ 10 Ripọtì
Arrange the following numbers in ascending order of magnitude 67
, 1315
, 0.8650
Akọwa Nkọwa
67
, 1315
, 0.8650
In ascending order, we have 0.8571, 0.8650, 0.8666
i.e. 67
< 0.8650 < 1315
Ajụjụ 11 Ripọtì
If 32y + 6(3y) = 27. Find y
Akọwa Nkọwa
32y + 6(3y) = 27
This can be rewritten as (3y)2 + 6(3y) = 27
Let 3y = x
x2 + 6x - 27 = 0
(x + 9)(x - 3) = 0
when x - 3 = 0, x = 3
sub. for x in 3y = x
3y = 3
log33 = y
y = 1
Ajụjụ 12 Ripọtì
Find correct to two decimals places 100 + 1100 + 31000 + 2710000
Akọwa Nkọwa
100 + 1100
+ 31000
+ 2710000
1000,000+100+30+2710000
= 1,000.15710000
= 100.02
Ajụjụ 13 Ripọtì
If cos θ = √32 and θ is less than 90o. Calculate cos90−θsin2θ
Akọwa Nkọwa
cos90−θsin2θ
= tanθsin2θ
Sin2θ
=14
cos(90−θ)sin2θ
= 1√3
= 4√3
Ajụjụ 14 Ripọtì
In the figure, GHIJKLMN is a cube of side a. Find the length of HN.
Akọwa Nkọwa
HJ2 = a2 + a2 = 2a2
HJ = √2a2=a√2
HN2 = a2 + (a√2 )2 = a2 + 2a2 = 3a2
HN = √3a2
= a√3 cm
Ajụjụ 15 Ripọtì
A bag contains 4 white balls and 6 red balls. Two balls are taken from the bag without replacement. What is the probability that they are both red?
Akọwa Nkọwa
P(R1) = 610
= 23
P(R1 n R11) = P(both red)
35
x 59
= 13
Ajụjụ 16 Ripọtì
Solve the simultaneous equations 2x - 3y + 10 = 10x - 6y = 5
Akọwa Nkọwa
2x - 3y = -10; 10x - 6y = -5
2x - 3y = -10 x 2
10x - 6y = 5
4x - 6y = -20 .......(i)
10x - 6y = 5.......(ii)
eqn(ii) - eqn(1)
6x = 15
x = 156
= 52
x = 212
Sub. for x in equ.(ii) 10(52
) - 6y = 5
y = 312
Ajụjụ 17 Ripọtì
Two points X and Y both on latitude 60oS have longitude 147oE and 153oW respectively. Find to the nearest kilometer the distance between X and Y measured along the parallel of latitude (Take 2π R = 4 x 104km, where R is the radius of the earth)
Akọwa Nkọwa
Length of an area = θ360
× 2π
r
Longitude difference = 147 + 153 = 300oN
distance between xy = θ360
× 2π
R cos60o
= 300360
× 4 × 104 × 12
= 1.667 × 104km (1667 km)
Ajụjụ 19 Ripọtì
At what real value of x do the curves whose equations are y = x3 + x and y = x2 + 1 intersect?
Akọwa Nkọwa
y = x3 + x and y = x2 + 1
x−2−1012Y=x3+x−10−20210y=x2+152125
The curves intersect at x = 1
Ajụjụ 22 Ripọtì
The ratio of the length of two similar rectangular blocks is 2 : 3. If the volume of the larger block is 351cm3, then the volume of the other block is
Akọwa Nkọwa
Let x represent total vol. 2 : 3 = 2 + 3 = 5
35
x = 351
x = 351×53
= 585
Volume of smaller block = 23
x 585
= 234.00
Ajụjụ 24 Ripọtì
If the quadratic function 3x2 - 7x + R is a perfect square, find R
Akọwa Nkọwa
3x2 - 7x + R. Computing the square, we have
x2 - 73
= -R3
(x1?76
)2 = -R3
+ 4936
?R3
+ 4936
= 0
R = 4936
x 31
= 4912
Ajụjụ 25 Ripọtì
If a{x+1x−2−x−1x+2 } = 6x. Find a in its simplest form
Akọwa Nkọwa
a{x+1x−2−x−1x+2
} = a{(x+1)(x+2)−(x−1)(x−2)(x−2)(x+2)
}
= 6
6xx2−4
= 6x
a = x2 - 4
Ajụjụ 26 Ripọtì
In the figure, the area of the shaded segment is
Akọwa Nkọwa
Area of sector = 120360×π×(3)2=3π
Area of triangle = 12×3×3×sin120o
= 92×√32=9√34
Area of shaded portion = 3π−9√34
= 3 π−3√34
Ajụjụ 27 Ripọtì
If the hypotenuse of right angled isosceles triangle is 2, what is the length of each of the other sides?
Akọwa Nkọwa
45o = x2
, Since 45o = 1√2
x = 2 x 1√2
= 2√22
= √2
Ajụjụ 28 Ripọtì
Solve for (x, y) in the equation 2x + y = 4: x^2 + xy = -12
Akọwa Nkọwa
2x + y = 4......(i)
x^2 + xy = -12........(ii)
from eqn (i), y = 4 - 2x
= x2 + x(4 - 2x)
= -12
x2 + 4x - 2x2 = -12
4x - x2 = -12
x2 - 4x - 12 = 0
(x - 6)(x + 2) = 0
sub. for x = 6, in eqn (i) y = -8, 8
=(6,-8); (-2, 8)
Ajụjụ 29 Ripọtì
If f(x - 2) = 4x2 + x + 7, find f(1)
Akọwa Nkọwa
f(x - 2) = 4x2 + x + 7
x - 2 = 1, x = 3
f(x - 2) = f(1)
= 4(3)2 + 3 + 7
= 36 + 10
= 46
Ajụjụ 30 Ripọtì
Without using table, calculate the value of 1 + sec2 30o
Akọwa Nkọwa
1 + sec2 30o = sec 30o
= 2√3
(2)23
= 43
1 + sec2 30o = sec 30o
= 1 + 4√3
= 213
Ajụjụ 31 Ripọtì
In △
XYZ, XY = 13cm, YZ = 9cm, XZ = 11cm and XYZ = θ
. Find cosθ
o
Akọwa Nkọwa
cosθ
= 132+92−1122(13)(9)
= 169+81−2126×9
cosθ
= 12926×9
= 4378
Ajụjụ 33 Ripọtì
Solve the following equation 22r−1 - 53 = 1r+2
Akọwa Nkọwa
22r−1
- 53
= 1r+2
22r−1
- 1r+2
= 53
2r+4−2r+12r−1(r+2)
= 53
5(2r+1)(r+2)
= 53
5(2r - 1)(r + 2) = 15
(10r - 5)(r + 2) = 15
10r2 + 20r - 5r - 10 = 15
10r2 + 15r = 25
10r2 + 15r - 25 = 0
2r2 + 3r - 5 = 0
(2r2 + 5r)(2r + 5) = r(2r + 5) - 1(2r + 5)
(r - 1)(2r + 5) = 0
r = 1 or −52
Ajụjụ 34 Ripọtì
The bearing of a bird on a tree from a hunter on the ground is ₦72oE. What is the bearing of the hunter from the birds?
Akọwa Nkọwa
Bearing of Hunter from Bird is
180 + 27 = 207o
Note that bearing is always taken from the north
207o = S 27o W
Ajụjụ 37 Ripọtì
Factorize abx2 + 8y - 4bx - 2axy
Akọwa Nkọwa
abx2 + 8y - 4bx - 2axy = (abx2 - 4bx) + (8y - 2axy)
= bx(ax - 4) 2y(ax - 4) 2y(ax - 4)
= (bx - 2y)(ax - 4)
Ajụjụ 39 Ripọtì
Find the area of a regular hexagon inscribed in a circle of radius 8cm
Akọwa Nkọwa
Area of a regular hexagon = 8 x 8 x sin 60o
= 32 x √32
=
Area = 16√3
x 6 = 96 √3
cm2
Ajụjụ 40 Ripọtì
In the equation below, Solve for x if all the numbers are in base 2: 11x = 1000x+101
Akọwa Nkọwa
11x
= 1000x+101
= 11(x + 101)
1000x = 11x + 1111
1000x - 11x = 1111
101x = 1111
x = 1111101
x = 11
Ajụjụ 41 Ripọtì
In a restaurant, the cost of providing a particular type of food is partly constant and partially inversely proportional to the number of people. If cost per head for 100 people is 30k and the cost for 40 people is 60k, Find the cost for 50 people?
Akọwa Nkọwa
C = a + k
1N
= c
= aN+kN
CN = aN + K
30(100) = a(100) + k
3000 = 100a + k.......(i)
60(40) = a(40) + k
2400 = 40a + k.......(ii)
eqn (i) - eqn (ii)
600 = 60a
a = 10
subt. for a in eqn (i) 3000 = 100(10) + K
3000 - 1000 = k
k = 2000
CN = 10N + 2000. when N = 50,
50C = 10(50) + 2000
50C = 500 + 2000
C = 250050
= 50k
Ajụjụ 42 Ripọtì
2212 % of the Nigerian Naira is equal to 17110 % of a foreign currency M. What is the conversion rate of the M to the Naira?
Akọwa Nkọwa
N = 2212
%, M = 17110
%
M = 17110
%, N = 452
452
x 10171
= 225171
= 1 54171
= 1 1857
Ajụjụ 43 Ripọtì
a sum of money was invested at 8% per annum simple interest. If after 4 years the money amounts to N330.00. Find the amount originally invested
Akọwa Nkọwa
S.I = PTR100
T = 4yrs, R = 8%, a = N330.00
330 - P = PTR100
, A = P + I
i.e. A = P + PTR100
330 = P + P(4)(8)100
33000 = 32P + 100p
132P = 33000
P = N250.00
Ajụjụ 44 Ripọtì
In the figure, PQ is the tangent from P to the circle QRS with SR as its diameter. If QRS = θ
∘
and RQP = ϕ
∘
, which of the following relationships between θ
∘
and ϕ
∘
is correct
Akọwa Nkọwa
180 - ϕ ∘ = θ ∘ + ϕ ∘ (Sum of opposite interior angle equal to its exterior angle)
180 = 2ϕ + θ ∘
Ajụjụ 45 Ripọtì
The factors of 9 - (x2 - 3x - 1)2 are
Akọwa Nkọwa
9 - (x2 - 3x - 1)2 = [3 - (x2 - 3x - 1)] [3 + (x2 - 3x - 1)]
= (3 - x2 + 3x + 1)(3 + x2 - 3x - 1)
= (4 + 3x - x2)(x2 - 3x + 2)
= (4 - x)(1 + x)(x - 1)(x - 2)
= -(x - 4)(x + 1) (x - 1)(x - 2)
Ajụjụ 46 Ripọtì
In the figure, MNQP is a cyclic quadrilateral. MN and Pq are produced to meet at X and NQ and MP are produced to meet at Y. If MNQ = 86∘
and NQP = 122∘
find (x∘
, y∘
)
Akọwa Nkọwa
y∘ = 180∘ - (86∘ + 58∘ )
180 - 144 = 36∘
x∘ = 180 - (94 + 58)
180 -152 = 28
(x∘ , y∘ ) = (28∘ , 36∘ )
Ajụjụ 47 Ripọtì
Which of these angles can be constructed using ruler and a pair of compasses only?
Ị ga-achọ ịga n'ihu na omume a?