x2468f4y65 x 2 4 6 8 f 4 y 6 5 If the mean of the above frequency distribution is 5.2, find y

Assessment: JAMB UTME - Mathematics - 1992 Subject: General Mathematics

Question 1 Report

$\begin{array}{cc} x & 2 & 4 & 6 & 8 \\ f & 4 & y & 6 & 5 \end{array}$

If the mean of the above frequency distribution is 5.2, find y

2, 1

1, 2

1, 5

5, 2

Answer Details

Mean $\bar{x}$ = $\frac{\sum f x}{\sum f}$
= $\frac{5.2}{1}$
= $\frac{8 + 4 y + 36 + 40}{4 + y + 6 + 5}$
= $\frac{5.2}{1}$
= $\frac{84 + 4 y}{15 + y}$
= 5.2(15 + y)
= 84 + 4y
= 5.2 x 15 + 5.2y
= 84 + 4y
= 78 + 5.2y
= 84 = 4y
= 5.2y - 4y
= 84 - 78
1.2y = 6
y = $\frac{6}{1.2}$
= $\frac{60}{12}$
= 5