Question

The Mean of the following distribution is 48 and the sum of all the frequencies is
50. Find the missing frequencies x and
Class Interval
20-30
30-40
40-50
50-60
60-70
Frequency
8
6
x
11
у​

Answer 1

In the given figure, we can see, LM || CB,

By using basic proportionality theorem, we get,

AM/MB = AL/LC …..(i)

Similarly, given, LN || CD and using basic proportionality theorem,

∴ AN/AD = AL/LC ……(ii)

From equation (i) and (ii), we get,

AM/MB = AN/AD

Hence, proved.