posted by ReRe Please Help!! on .
One pump can drain the pool in 11 minutes. When a second pump is used, it only takes 9 minutes. How long would it take the second pump to drain the pool if it were the only pump in use?
Pump 1 drains 1/11 pools per minute
Pump 2 drains 1/x pools per minute
(1/11 +1/x)pools/min * 9min = 1 pool
(1/11 + 1/x) =1/9
1/x = 1/9 -1/11 = 11/99 -9/99 = 2/99
so the second pump does 2/99 pool;s per minute or
99/2 minutes per pool
Damon, Im not for sure what the 2/99 stands for.
If the pool has 99 units, then the pump will drain 2 of these units per minute.