SOLUTION: If tom can fill a swimming pool in 30 min, sally can fill one in 45 min, and Joe can fill one in 90 min. How long will it take for them to fill a swimming pol together?

Algebra ->  Rational-functions -> SOLUTION: If tom can fill a swimming pool in 30 min, sally can fill one in 45 min, and Joe can fill one in 90 min. How long will it take for them to fill a swimming pol together?      Log On


   



Question 151235: If tom can fill a swimming pool in 30 min, sally can fill one in 45 min, and Joe can fill one in 90 min. How long will it take for them to fill a swimming pol together?
Answer by ankor@dixie-net.com(22740) About Me  (Show Source):
You can put this solution on YOUR website!
If tom can fill a swimming pool in 30 min, sally can fill one in 45 min, and Joe can fill one in 90 min. How long will it take for them to fill a swimming pol together?
;
Let t = time required if they work together
Let the full pool = 1
:
t%2F30 + t%2F45 + t%2F90 = 1
Multiplying the equation by 90 will get rid of the denominators, results:
:
3t + 2t + t = 90
:
6t = 90
t = 90%2F6
t = 15 min
;
:
Check solution:
15%2F30 + 15%2F45 + 15%2F90 =
45%2F90 + 30%2F90 + 15%2F90 = 1