It takes 4 hours to complete the entire fence
Solution:
Given that construction company is building a fence that is
miles long
They build
of the fence every hour
To find: number of hours required to complete the fence
From given information,
Length of fence =

Time taken to build
mile of fence = 1 hour
Then time taken to build 1 mile of fence = Time taken to build
mile of fence divided by 1/6

Thus 6 hours are needed to build 1 mile of fence
So to build entire length of fence, time taken is given as:
time taken = total length of fence x time taken for 1 mile of fence

Thus it takes 4 hours to complete the entire fence