question_answer

The following table gives the weekly consumption of electricity of 56 families

Weekly consumption	0-10	10-20	20-30	30-40	40-50
Number of families	16	12	18	6	4

Find the mean.  

Answer:

Cl	Mid value			-25
0-10 10-20 20-30 30-40 40-50	5 15 25 35 45	16 12 18 6 4	-20 -10 0 10 20	-2 -1 0 1 2	-32 -12 0 6 8
		N=56

Here,and Using step deviation method Mean                             (1)                          (1/2)                                       (1) Mean =19.7