Question

210 men working 12 hours a day can finish a job in 18 days. How many men are required to finish the job in 20 days working 14 hours a day?

Answer 1

Let the required number of men be $x$.

More working hours $=$ less men required.
$\therefore$ It is inverse proportion.
$\therefore$ Multiplying factor is $\frac{12}{14}$
Also more number of days = less men
$\therefore$ It is an inverse proportion
$\therefore$ Multiplying factor is $\frac{18}{20}$
$$\therefore x=210\times \frac{12}{14}\times \frac{18}{20}$$
$$\begin{array}{cc}& \frac{210\times 12\times 18}{14\times 20}\\ & x=162men\end{array}$$
162 men are required.