Question

Working alone, it takes Scott 16 minutes to inflate twenty balloons, Ashley can inflate the same twenty balloons in 15 minutes. Find how long it would take them if they worked together.

Answer 1

7.74 minutes

Explanation:

Scott's rate = 20 /16 = 1.25

Ashley's rate = 20 / 15 = 1.333

Combined rate = (1.25 + 1.3333) = 2.583333

Hence, time it will take to inflate 20 balloons :

Rate = number of balloons / time taken

2.583333 = 20 / time taken

Time taken = 20 / 2.583333

Time taken = 7.7419

It will take them approximately 7.7 minutes to inflate 20 balloons