### The following table shows the number of working hours and the number of employees employed in a small scale industry $\begin{array}{|c|c|} \hline \text { No. of working hours } & \text { No. of employees } \\ \hline 3-5 & 7 \\ \hline 5-7 & 10 \\ \hline 7-9 & 18 \\ \hline 9-11 & 57 \\ \hline 11-13 & 14 \\ \hline 13-15 & 8 \\ \hline \end{array}$ The average number of working hours of an employee is.

A. 8.5 B. 9.5 C. 10.5 D. None of these Answer: Option B

### Solution(By Apex Team)

We have : $\begin{array}{|c|c|c|c|c|c|c|} \hline \text { Mean working hours } & 4 & 6 & 8 & 10 & 12 & 14 \\ \hline \text { No. of employees } & 7 & 10 & 18 & 57 & 14 & 8 \\ \hline \end{array}$ Sum of working hours of all the employees = (4 × 7 + 6 × 10 + 8 × 18 + 10 × 57 + 12 × 14 + 14 × 8) = (28 + 60 + 144 + 570 + 168 + 112) = 1082 Total number of employees = (7 + 10 + 18 + 57 + 14 + 8) = 114 ∴ Average number of working hours $\begin{array}{l}=\left(\Large\frac{1082}{114}\right)\\ =9.49\approx9.5\end{array}$

A. 20
B. 21
C. 28
D. 32

A. 18
B. 20
C. 24
D. 30

A. 10 years
B. 10.5 years
C. 11 years
D. 12 years