The following table gives the literacy rate (in percentage) of 35 cities. Find the mean literacy rate.

Let the assumed mean A = 70 and h = 10.

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

Now, we have $N=\sum f_{i}=35, \sum f_{i} u_{i}=-2, h=10$ and $A=70$

Putting the values in the above formula, we have

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

$=70+10\left(\frac{1}{35} \times(-2)\right)$

$=70-\frac{20}{35}$

$=70-0.571$

$=69.428$