Question

It takes 3 identical water pumps 8 hours to fill a pool. How long would it take 4 of

Answer 1

Answer:

Step-by-step explanation:

We have 3 identical pumps working to fill a pool. If it takes them working  together 8 hours to fill the pool, the equation is:

$\frac{1}{x}+\frac{1}{x}+\frac{1}{x}=\frac{1}{8}$ and

$\frac{3}{x}=\frac{1}{8}$ . Cross multiply to get

x = 24, which is the number of hours it will take one pump to do the job all alone. If this be the case, and we have 4 pumps WORKING AT THE SAME TIME, filling the pool will be the number of hours it takes one pump divided by 4.

4 pumps can do the job in 6 hours.