SOLUTION: One pipe can fill a tank in 8 minutes and a second pipe can fill it in 12 minutes. If the tank is empty, how long will it take both pipes to fill it? Thank you for looking.

Question 60890: One pipe can fill a tank in 8 minutes and a second pipe can fill it in 12 minutes. If the tank is empty, how long will it take both pipes to fill it?
Thank you for looking.
Found 2 solutions by checkley71, Earlsdon:
Answer by checkley71(8403) (Show Source): You can put this solution on YOUR website!
TWODIFFERENT ITEMS WORKING TOGETHER TO ACCOMPLISH A TASK IS GIVEN BY
X*Y/(X+Y) THUS
8*12/(8+12)
96/20=4.8 MINUTES TO FILL THE TANK WHEN BOTH PIPES ARE USED

Answer by Earlsdon(6294) (Show Source): You can put this solution on YOUR website!
One approach to this kind of problem is to first calculate the rate that each pipe can fill the tank.
If it takes pipe A 8 minutes to fill the tank, then pipe A can fill 1/8 of the tank in 1 minute.
If it takes pipe B 12 minutes to fill the tank, then pipe B can fill 1/12 of the tank in 1 minute.
Working together, pipe A and pipe B can fill (1/8 + 1/12) of the tank in 1 minute.
1/8 + 1/12 = (3+2)/24 = 5/24 of the tank in 1 minute.
5/24 of tank = 1 min. Multiply both sides by the reciprocal (24/5)
1 = 24/5 mins. = 4.8 mins.
The tank can be filled in 4.8 minutes by both pipes working together.
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