SOLUTION: An inlet pipe on a swimming pool can be used to fill the pool in 10 hours. The drain pipe can be used to empty the pool in 30 hours. If the pool is 15 filled and then the inlet pip

Algebra ->  Rate-of-work-word-problems -> SOLUTION: An inlet pipe on a swimming pool can be used to fill the pool in 10 hours. The drain pipe can be used to empty the pool in 30 hours. If the pool is 15 filled and then the inlet pip      Log On


   

Question 951005: An inlet pipe on a swimming pool can be used to fill the pool in 10 hours. The drain pipe can be used to empty the pool in 30 hours. If the pool is 15 filled and then the inlet pipe and drain pipe are opened, how long from that time will it take to fill the pool?
Answer by josgarithmetic(39620) About Me  (Show Source):
You can put this solution on YOUR website!
PIPE_______________RATES
Inlet_______________1%2F10
Outlet_____________-1%2F30
Combined__________1%2F10-1%2F30=1%2F15

"If the pool is 15 filled and then the..."

Fifteen what? This description need to be more specific or nothing can be solved.
Is this the numerator of a fraction? Fraction of what? Is this percent of the pool?
Is it a specific volume (not likely)? Is this a time quantity? If time, then is
this minutes or hours?

Here is a guess the piece of information is "15 minutes".

If fill pipe was open for 15 minutes, this is 1%2F4 hour, and you can ask what is t in hour
to fill the pool after both pipes became open.
-
%281%2F10%29%2A%281%2F4%29, amount of pool filled already
highlight_green%28%281%2F15%29%2At=1-%281%2F10%29%281%2F4%29%29, amount still to be filled
;
Solve for t.