Oct 2
Can Empty
Posted on Saturday, October 2, 2010 in Collectibles
How long will an empty tank be filled if the pumps work simultaneously together?
The 1st and 2nd pumps can fill the tank in 4 hours and 6 hours, respectively. The 3rd pump can empty the tank in 8 hours.
No. of hours for an empty tank to be filled—h:
x/4 + x/6 - x/8 = 1
6x + 4x - 3x = 24
7x = 24
x = 24/7 or 3 3/7
Answer: 3 3/7 hours OR 3 hours, 25 minutes & 42 6/7 seconds