Question

Find the mean wages in rupees of $200$ workers of a factory where wages are classified as follows:

Class	100-150	150-200	200-250	250-300	300-350	350-400	400-450	450-500	500-550
Frequency	4	8	14	42	50	40	32	6	4

Answer 1

Calculation for mean

Class	Mid value (x)	frequency $f$	$y=\frac{x-325}{50}$	$fy$
100-150	125	4	-4	-16
150-200	175	8	-3	-24
200-250	225	14	-2	-28
250-300	275	42	-1	-42
300-350	325	50	0	0
350-400	375	40	1	40
400-450	425	32	2	64
450-500	475	6	3	18
500-550	525	4	4	16
		N=200		$\sum fy=138-110=28$

Mean$\left(\overline{x}\right)=A+\frac{\sum fy}{N}\times d=325+\frac{28}{200}\times 50=325+7=Rs332$