SOLUTION: Working together, two pumps can drain a certain pool in 6 hours. If it takes the older pump 15 hours to drain the pool by itself, how long will it take the newer pump to drain the

Algebra ->  Rate-of-work-word-problems -> SOLUTION: Working together, two pumps can drain a certain pool in 6 hours. If it takes the older pump 15 hours to drain the pool by itself, how long will it take the newer pump to drain the       Log On


   

Question 970260: Working together, two pumps can drain a certain pool in 6 hours. If it takes the older pump 15 hours to drain the pool by itself, how long will it take the newer pump to drain the pool on its own?
Found 2 solutions by josmiceli, thesvw:
Answer by josmiceli(19441) About Me  (Show Source):
You can put this solution on YOUR website!
Add the pumping rates of the 2 pumps
to get their rate working together
Rate for older pump:
[ 1 pool drained ] / [ 15 hrs ]
Rate for newer pump:
[ 1 pool drained ] / [ t hrs ]
Rate working together:
[ 1 pool drained ] / [ 6 hrs ]
----------------------------
+1%2F15+%2B+1%2Ft+=+1%2F6+
Multiply both sides by +30t+
+2t+%2B+30+=+5t+
+3t+=+30+
+t+=+10+
The newer pump can drain the pool in
10 hrs working on it's own
-------------------------
check:
+1%2F15+%2B+1%2Ft+=+1%2F6+
+1%2F15+%2B+1%2F10+=+1%2F6+
+2%2F30+%2B+3%2F30+=+5%2F30+
+2+%2B+3+=+5+
+5+=+5+
OK

Answer by thesvw(77) About Me  (Show Source):
You can put this solution on YOUR website!
Together = V/6 Older = V/15 Newer = V/t
1/6 = 1/15 + 1/t
15 -6 = 90/t
t = 10 hours