Question

A pipe can fill a tank in 3 hours. A second pipe can fill the tank in 5 hours.

How long will it take to fill the tank with both pipes running at the same time?

Answer 1

15 hrs

Explanation:

Time for One pipe = 3 hrs

Amount of tank it can fill in 1 hr = 1/3

Time for Second pipe = 5 hrs

Amount of tank it can fill in 1 hr = 1/5

Tank they can fill together in 1 hr = 1/3 x 1/5= 1/15

Time it takes to fill full tank = 15/1

I hope im right!!

Answer 2

15 hours

Explanation:

3: 3, 6, 9, 12, 15

5: 5, 10, 15, 20

15 is the lcm of 3 and 5