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 x be the number days required to complete a piece of work by 125 men.
 

Number of men	50	125
Months	5	x

$$\text{ Since the number of men engaged and the number of days taken to do a piece of work are in inverse variation, we have: }$$
$$50\times 5=125x$$
$$\Rightarrow x=\frac{50\times 5}{125}$$
$$=2$$
$$\text{ Thus, the required number of months is 2 }.$$