Question

Find the mean of the following data, using direct method:
$\begin{array}{ccccccc}\text{Class}& 0-10& 10-20& 20-30& 30-40& 40-50& 50-60\\ \text{Frequency}& 7& 5& 6& 12& 8& 2\end{array}$

Answer 1

Class	Frequency ($f_i$)	Mid Values ($x_i$)	($f_i{x}_i$)
0 - 10	7	5	35
10-20	5	15	75
20 -30	6	25	150
30 -40	12	35	420
40 -50	8	45	360
50 - 60	2	55	110
Total	$\sum f_i$ = 40		$\sum f_i{x}_i$ =1150

Therefore, Mean, $\overline{x}=\frac{\sum f_i{x}_i}{\sum f_i}$

= 1150/40 = 28.75

Therefore, $\overline{x}$= 28.75