Question

Engineers are digging a 3200-foot-long tunnel at a constant rate. After 5 months, the engineers still need to dig 1700 feet to finish the project. How much time does it take to complete the tunnel from start to finish?

Answer 1

length od the tunnel = 3200 ft

after 5 months they need to dig 1700 ft more.

First, calculate the ft dug

3200-1700 = 1500 ft

Apply the rate

ft / time

1500 / 5

For the total length:

3200/ t

Equal both rates:

1500/5 = 3200/t

t = 3200 / (1500/5)

t= 3200/ 300

t= 10.6 months