Question

20 men can complete a task in 4 days. How many men will be able to complete the same task in 2 days?

• A. 30
• B. 40
• C. 35
• D. 45

Answer 1

The correct option is B

40

Let the number of men needed to finish the task in 2 days be $x$. Note that the ratio of men in this case is $20:x$ and the ratio of the number of days needed is $4:2$.
As the number of men available for work increases, the time needed to complete the task decreases (and vice-versa).
Thus, the number of workers and the number of days needed to finish the task are in inverse proportion.
Thus, we have $20:x=2:4(Inverseof4:2)$
$⟹2\times x=20\times 4(Productofextremes=Productofmeans)$
$⟹x=40$
Thus, 40 men are needed to complete the task in 2 days.