Question

Find the missing frequencies in the following frequency distribution if it is known that the mean of the distribution is 50.

x:	10	30	50	70	90
f:	17	f1	32	f2	19	Total 120

Answer 1

Given:

Mean

First of all prepare the frequency table in such a way that its first column consists of the values of the variate and the second column the corresponding frequencies.

Thereafter multiply the frequency of each row with corresponding values of variable to obtain third column containing.

Then, sum of all entries in the column second and denoted by and in the third column to obtain.

Now,

..... (1)

We know that mean,

By using cross multiplication method,

..... (2)

Putting the value of from equation (1) in (2), we get

Therefore,

Putting the value of in equation (1), we get

Hence,