#### The following table gives the number of pages written by Sarika for completing her own book for 30 days : no.of pages written per day 16-18 19-21 22-24 25-27 28-30 no.of days 1 3 4 9 13 Find the mean number of pages written per day.

Solution.  Here we calculate mean by following the given steps:

1. Find the mid point of each interval.
2. Multiply the frequency of each interval by its mid point.
3. Get the sum of all the frequencies (f) and sum of all the (fx)
4. Now divide sum of (fx) by sum of (f)
 No.of pages written per day no.of days(fi) (xi) fixi 16-18 1 17 17 19-21 3 20 60 22-24 4 23 92 25-27 9 26 234 28-30 13 29 377 $\sum f_{i}= 30$ $\sum f_{i}x_{i}= 780$

$mean\left ( \bar{x} \right )= \frac{\sum f_{i}x_{i}}{\sum f_{i}}= \frac{780}{30}= 26$