SOLUTION: One pump can fill a water tank in 40 minutes and another pump takes 30 minutes. When the tank was empty, both pumps were turned on for 10 minutes and then the slower pump was turne

Question 489384: One pump can fill a water tank in 40 minutes and another pump takes 30 minutes. When the tank was empty, both pumps were turned on for 10 minutes and then the slower pump was turned off. How much longer did the faster pump have to run before the tank was filled?
Answer by stanbon(75887) (Show Source): You can put this solution on YOUR website!
One pump can fill a water tank in 40 minutes and another pump takes 30 minutes. When the tank was empty, both pumps were turned on for 10 minutes and then the slower pump was turned off. How much longer did the faster pump have to run before the tank was filled?
--------------------------------
1st pump rate = 1/40 job/min
---
2nd pump rate = 1/30 job/min
---
Together rate = 1/40 + 1/30 = (70)/1200 = 7/120 job/min
==============================
Equation:
work done + work done = one job done
(7/120)10 + (1/30)x = 1 job
Multiply thru by 120 to get:
70 + 4x = 120
4x = 50
x = 12.5 minutes (time the faster pump had to run)
============
Cheers,
Stan H.
RELATED QUESTIONS
One pump can fill a water tank in 3h (hours), and another pump takes 5h. When the tank... (answered by ptaylor)

please help me sol this equation: One pump can fill a water tank in 3 h, and another pump (answered by ankor@dixie-net.com)

one pump can fill a tank in 12 minutes while another takes 16 minutes to empty the same... (answered by solver91311)

One pump fills a tank 4 times as fast as another pump. If the pumps work together, they... (answered by vleith)

A water tank can be filled by a gasoline fueled water pump in 28 minutes and by an... (answered by Cromlix)

If one pump takes 12 minutes to fill a tank and another pump takes 20 minutes to fill the (answered by feliz1965)

A water tank is connected to the two pumps. It takes 40 minutes to fill the tank from the (answered by mananth)

Pump A can fill a tank of water in 4 hours. Pump B can fill the same tank in 6 hours.... (answered by josgarithmetic)

Two pumps working together can fill a water tank in 18 minutes. one pump works twice as... (answered by lwsshak3)