Find the mean of each of the following frequency distributions :

Let the assumed mean be A = 60 and h = 20.

We know that mean, $\bar{X}=A+h\left(\frac{1}{N} \sum f_{i} u_{i}\right)$

Now, we have $N=\sum f_{i}=50, \sum f_{i} u_{i}=14, h=20$ and $A=60$.

Putting the values in the above formula, we have

$\bar{X}=A+h\left(\frac{1}{N} \sum f_{i} u_{i}\right)$

$=60+20\left(\frac{1}{50} \times(14)\right)$

$=60+\frac{280}{50}$

$=60+5.6$

$=65.6$

Hence, the mean is 65.6.