#### The weights of tea in 70 packets are shown in the following table :  Weight (in gram) Number of packets 200-201 201-202 202-203 203-204 204-205 205-206 13 27 18 10 1 1 Find the mean weight of packets.

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)
 Weight xi fi fixi 200-201 200.5 13 2606.5 201-202 201.5 27 5440.5 202-203 202.5 18 3645.0 203-204 203.5 10 2035.0 204-205 204.5 1 204.5 205-206 205.5 1 205.5 $\sum f_{i}= 70$ $\sum f_{i}x_{i}= 14137$

$mean\left ( \bar{x} \right )= \frac{\sum f_{i}x_{i}}{\sum f_{i}}= \frac{14137}{70}= 201\cdot 95$