Question

a coin sorting machine can sort a certain number of coins in 15 min a second machine can sort the same number of coins in 30 min how long would it take both machines working together to do the job?

Answer 1

10 minutes.

Explanation:

In this case we have that one machine ends in a quantity "m" of coins in 15 minutes and the other machine the same amount "m" in 30 minutes, that is:

Machine 1: m / 15

Machine 2: m / 30

Therefore, to know the performance of the two together, we must add:

m / 15 + m / 30 = m / x

We cancel m, and we are left with:

1/15 + 1/30 = 1 / x

0.1 = 1 / x

x = 1 / 0.1

x = 10

Therefore, the two machines together would take 10 minutes.