Question

If a crew of 4 workers complete the job in 10 hours, how long will it take 5 workers to complete the same job?

Answer 1

We can solve using proportions
$\frac{4}{10} = \frac{5}{x}$
or 4 works is to 10 hours as 5 workers is to x hours.
to solve we cross multiply to get
$4x = 50 \\ x = \frac{50}{4}$
so it will take 5 men 12.5 hours!