SOLUTION: a tank can be filled in 18 hours by pipe A or in 24 hours by pipe B. How long would it take both pipes to fill the tank?

Algebra ->  Human-and-algebraic-language -> SOLUTION: a tank can be filled in 18 hours by pipe A or in 24 hours by pipe B. How long would it take both pipes to fill the tank?      Log On


   



Question 458152: a tank can be filled in 18 hours by pipe A or in 24 hours by pipe B. How long would it take both pipes to fill the tank?
Answer by josmiceli(19441) About Me  (Show Source):
You can put this solution on YOUR website!
Add the rates of flow of both pipes
+1%2F18+%2B+1%2F24+=+1%2Fx+
This is read as:
(1 tankful)/(A's time to fill it) + ( 1 tankful)/(B's time to fill it) = (1 tankful)/(A and B's time to fill it)
Multiply both sides by +72x+
+4x+%2B+3x+=+72+
+7x+=+72+
++x+=+10.286+
+.286%2A60+=+17.143+
+.143%2A60+=+8.57+
It takes both pipes 10 hrs 17 min 9 sec
check:
+1%2F18+%2B+1%2F24+=+1%2F10.286+
+.0556+%2B+.04167+=+.0972+
+.0973+=+.0972+
close enough