Question 499575
 Jim can fill a pool carrying buckets of water in 30 minutes. Sue can do the same job in 45 minutes. Tony can do the same job in 1 ½ hours. How quickly can all three fill the pool together?
Jim: 1 pool per 30 minutes
Sue: 1 pool per 45 minutes
Tony: 1 pool per 90 minutes (convert 1.5 hours to minutes)
.
Let x = time (minutes) it takes for all three
then
x(1/30 + 1/45 + 1/90) = 1
multiplying both sides by 90:
x(3 + 2 + 1) = 90
x(6) = 90
x = 90/6
x = 15 minutes