Question

Five workers together can build a road in 20 days. Suppose every worker works at the same rate. Three workers work on the road for 10 days before eleven more workers join them. How much longer will it take the fourteen workers to finish the road?

Answer 1

5 days

Explanation:

This problem is an inverse proportion case. Having two variables: number of workers and time (in days); when we increase the number of workers, the time needed decreases; vice versa. Therefore, we can use the multiplication method: (workers * time) will always stay constant.

Let's say the time (in days) needed by the eleven workers is t,

5*20 = (3*10) + (14*t)

100 = 30+14t

70 = 14t

5 = t

It will take the eleven-workers 5 more days to finish the road.