Age 3 4 5 6 7 8 9 10 No. of children 2 6 5 4 6 9 8 5 The table shows the distribution of ages of a number of children in a school. If the mean of the distri...

Assessment: WAEC SSCE - General Mathematics - 2022 (Essay) Subject: General Mathematics

Question 1 Report

Age 3 4 5 6 7 8 9 10
No. of children 2 6 5 4 6 9 8 5

The table shows the distribution of ages of a number of children in a school. If the mean of the distribution is 7, find the;

(a) value of x, (b) standard deviation of their ages.

Answer Details

Mean = (3x2 +4x6 + 5x5 + 6x + 7x6 + 8x9 + 9x8 + 10x5)  ÷ (2 + 6 + 5 + x + 6 + 9 + 8 + 5)

7 = (291 + 6x) ÷ (41+x)

7(41+x) = 291 + 6x

287 + 7x = 291 + 6x

x = 4

 

(b)

Age(x in yrs) No.of child Fx2 2
3 2 18
4 6 96
5 5 125
6 4 144
7 6 294
8 9 576
9 8 648
10 5 500
  Σf = 45

Σfx2 2  = 2401 

Standard deviation = 19645−−−√=4–√.3555

= 2.087

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