Suppose that the amount of time it takes to build a highway varies directly with the length of the highway and inversely with the number of workers. Suppose also that it takes 100 workers 6 weeks to build 4 miles of highway. How many workers would be needed to build 16 miles of highway in 15 weeks?

Answer 1

t = k d / n

6 = k 4 / 100
k = 600/4 = 150
so
t = 150 * d / n
then
15 = 150 * 16 / n
1/10 = 16/n
= 16/160