Question

A work force of 50 men with a contractor can finish a piece of work in 5 months.
In how many months the same work can be completed by 125 men.

Answer 1

Let in x months, the work will be completed by 125 men
$\begin{array}{ccc}\text{Men}& 50& 125\\ \text{Period (in months)}& 5& x\end{array}$
More men, less period
$\therefore$ By inverse variation
$50:125=x:5\Rightarrow \frac{50}{125}=\frac{x}{5}\Rightarrow 50\times 5=125\times x\Rightarrow x=\frac{50\times 5}{125}=2$
$\therefore$ Period = 2months.