SOLUTION: A large pump takes only 6 hours to fill a pool while a smaller pump takes 9 hours by itself to fill the same pool. How long will it take to fill the pool if both pumps work togethe

Algebra ->  Rate-of-work-word-problems -> SOLUTION: A large pump takes only 6 hours to fill a pool while a smaller pump takes 9 hours by itself to fill the same pool. How long will it take to fill the pool if both pumps work togethe      Log On


   



Question 904086: A large pump takes only 6 hours to fill a pool while a smaller pump takes 9 hours by itself to fill the same pool. How long will it take to fill the pool if both pumps work together?
Answer by richwmiller(17219) About Me  (Show Source):
You can put this solution on YOUR website!
a=6
b=9
1/a+1/b=1/x
1/6+1/9=1/x
1/6+1/9=1/3.6
1/x=1/3.6
x=3.6 hours working together
check
1/a+1/b=1/x
1/6+1/9=1/x
9/54+6/54=1/x
15/54=1/x
54/15=x
x=3.6 hours working together
ok