Question

Following information pertains to the daily income of 150 families. Calculate the arithmetic mean.

Income (in Rs)	Number of families
More than 75	150
More than 85	140
More than 95	115
More than 105	95
More than 115	70
More than 125	60
More than 135	40
More than 145	25

Answer 1

Income	No. of families	Frequency	Mid Value	fm
Class Interval	(CF)	(f)	(m)
75 – 85	150	150 – 140 = 10	80	800
85 – 95	140	140 – 115 = 25	90	2250
95 – 105	115	115 – 95 = 20	100	2000
105 – 115	95	95 – 70 = 25	110	2750
115 – 125	70	70 – 60 = 10	120	1200
125 – 135	60	60 – 40 = 20	130	2600
135 – 145	40	40 – 25 = 15	140	2100
145 – 155	25	25	150	3750
Total

= Rs 116.33