The arithmetic mean is simply called 'Average'. For the observations x_{1}, x_{2}, ….., x_{n }* *the A.M. is defined as

For simple frequency distribution,

For grouped frequency distribution, *X; *is taken as class mark.

The A.M. is sometimes called as 'Average' or 'Sample Mean'.

**Example 1. ***Find the mean of the following data.*

**Solution. **Here N = Total no. of matches = 30