Test Index

JAMB Mathematics 2019 Paper

Question : 15

Total: 73

Score (x)	0	1	2	3	4	5	6
Freq (f)	5	7	3	7	11	6	7

Solution:

Concept:

Variance measures how spread out the scores are from the mean score.

It is calculated using the formula for grouped data.

Explanation:

First, find the total frequency and the sum of

fx

\sum f = 5 + 7 + 3 + 7 + 11 + 6 + 7 = 46

\sum fx = 0(5) + 1(7) + 2(3) + 3(7) + 4(11) + 5(6) + 6(7) = 150

Mean,

\bar{x} = \frac{\sum fx}{\sum f} = \frac{150}{46} = 3.26

Next, calculate the squared deviations

f(x - \bar{x})^2

for each score.

The sum of these squared deviations is approximately

170.88

Variance,

\sigma^2 = \frac{\sum f(x - \bar{x})^2}{\sum f} = \frac{170.88}{46}

\sigma^2 = 3.715 \approx 3.72

Answer:

Option D:

3.72

Go to Question:

Prev Question

Next Question