SOLUTION: Pump A can fill a tank in 15 hours, pump B can fill the same tank in 19 hours 20mins. If both pumps were pumping, how long will it take to fill the tank?? Part 2. If pump A was p

Algebra ->  Polynomials-and-rational-expressions -> SOLUTION: Pump A can fill a tank in 15 hours, pump B can fill the same tank in 19 hours 20mins. If both pumps were pumping, how long will it take to fill the tank?? Part 2. If pump A was p      Log On


   

Question 691243: Pump A can fill a tank in 15 hours, pump B can fill the same tank in 19 hours 20mins. If both pumps were pumping, how long will it take to fill the tank??
Part 2. If pump A was pumping into the tank and pump B was pumping out of the tank, how long will it take to fill the tank??
Thanks everyone!!
Answer by ankor@dixie-net.com(22740) About Me  (Show Source):
You can put this solution on YOUR website!
Pump A can fill a tank in 15 hours, pump B can fill the same tank in 19 hours 20mins.
If both pumps were pumping, how long will it take to fill the tank??
:
Let t = time to fill the tank with both pumps working
Let the completed job = 1, (a full tank)
Change 19 hr 20 min to 19.33 hrs
:
each will do a fraction of the job, the two fractions add up to 1
:
t%2F15 + t%2F19.333 = 1
multiply by 290 (15*191%2F3), results
19.333t + 15t = 290
34.333t = 290
t = 290/34.333
t = 8.4466 hrs or 8 + .4466*60 = 8 hrs 26.8 minutes pumping together
:
Part 2. If pump A was pumping into the tank and pump B was pumping out of the tank, how long will it take to fill the tank??
:
Same values except pump B is subtracted
t%2F15 - t%2F19.333 = 1
multiply by 290 (15*191%2F3), results
19.333t - 15t = 290
4.333t = 290
t = 290/4.333
t = 66.923 hrs or 66 + .923*60 = 66 hrs 55.4 minutes