question_answer

   Let assumed mean, a = 35. Here h = 10

Classes	Mid ?value
0-10 10-20 20-30 30-40 40-50 80-60 60-70	5 15 25 35 45 55 65	4 4 7 10 12 8 5	-3 -2 -1 0 1 2 3	-12 -8 -7 0 12 16 15

Now mean OR

Classes	Mid value	Frequency
0-20 20-40 40-60 60-80 80-100	10 30 50 70 90	17 P 32 24 19	170 30p 1600 1680 1710

Since mean = 50

Answer:

  Find mean of the following frequency distribution, using step-deviation method :

Classes	0-10	10-20	20-30	30-40	40-50	50-60	60-70	Total
Frequency	4	4	7	10	12	8	5	50

OR The mean of the following frequency distribution is 50. Find the value of p.

Classes	0-20	20-40	40-60	60-80	80-100
Frequency	17	P	32	24	19