There were 90 runners to start a race. In the first half of the race, 1/3 of them dropped out. In the second half of the race, 2/5 of the remaining runners dropped out. How many runners finished?

Answer 1

You want to find the number of runners REMAINING. So one way to think about it is that if 1/3 drop out (first half of the race), then 2/3 of the original number remain. So after the 1st half 2/3 (90) = 60 runners remain.

During the 2nd half 2/5 drop out so 3/5 remain, and 3/5 (60) = 3(12) = 36 runners remain.

Of course you could think like this:

1/3 (90) = 30 drop out, so 90-30 = 60 remain.

2/5 (60) = 24 drop out, so 60 - 24 = 36 remain.