Question

The examination marks of $250$ pupils are recorded below. Find the mean.

Class interval	0-9	10-19	20-29	30-39	40-49
Frequency	0	2	6	24	36
Class interval	50-59	60-69	70-79	80-89	90-99
Frequency	47	55	40	27	13

• A. $50.12$
• B. $90.31$
• C. $60.82$
• D. $75.12$

Answer 1

The correct option is C $60.82$

$Mean=\frac{Total(midvalue\times frequency)}{Totalfrequency}$

Class interval	Mid- value	Fequency.	Mid-value $\times$ frequency
0-9	4.5	0	0
10-19	14.5	2	29
20-29	24.5	6	147
30-39	34.5	24	828
40-49	44.5	36	1602
50-59	54.5	47	2561.5
60-69	64.5	55	3547.5
70-79	74.5	40	2980
80-89	84.5	27	2281.5
99-99	94.5	13	1228.5
		Total - 250	Total 15205

$Mean=\frac{Total(midvalue\times frequency)}{Totalfrequenct}=\frac{15205}{250}=60.82$