5 people were asked about the time in a week they spend in doing social work in their community. They replied 10, 7, 13, 20 and 15 hours, respectively. Find the mean time in a week devoted by them for social work.

Mean (M) = $\dfrac{\text{Total social work hrs}}{\text{No. of people}}$

Sum of hours spent by people on social work = 10 + 7 + 13 + 20 + 15 = 65.

$M = \dfrac{65}{5} = 13.$

Hence, the mean time in a week devoted by people for social work is 13 hours.