Question 3

The following distribution shows the daily pocket allowance of children of a locality. The mean pocket allowance is Rs 18. Find the missing frequency $f$.

$$\begin{array}{|c|c|c|c|c|c|c|c|}

\hline
\text{Daily pocket allowance (Rs)} & 11 - 13 & 13 - 15 & 15 - 17 & 17 - 19 & 19 - 21 & 21 - 23 & 23 - 25 \\
\hline
\text{Number of children} & 7 & 6 & 9 & 1 & 3 & f & 5 \\
\hline
\end{array}$$