Marge has 3 pumps for filling her swimming pool. When all 3 pumps work at their maximum rates, the swimming pool is filled in 56 minutes. Pump 1's maximum rate is twice the maximum rate of pump 2 and four times the maximum rate of pump 3. How long would it take Marge to fill the pool if she used only pump 3 at its maximum rate ?
Pick.
A) 2hrs, 48mins	B) 6hrs, 32mins	C) 7hrs, 12mins	D) 13hrs, 4mins	E) 14hrs, 24mins
The rate of pump 1 = 4x job/minute.   The rate of pump 2 = 2x job/minute.   The rate of pump 3 = x job/minute.   Given that x+2x+4x=1/56 --&gt; x=1/392 --&gt; (time) = (reciprocal of rate) = 392 minutes = 6 hours and 32 minutes.   Answer: 6hrs, 32mins.
<result>B</result>
Marge has 3 pumps for filling her swimming pool. When all 3 pumps work at their maximum rates, the swimming pool is filled in 56 minutes. Pump 1's maximum rate is twice the maximum rate of pump 2 and four times the maximum rate of pump 3. How long would it take Marge to fill the pool if she used only pump 3 at its maximum rate ?