Question

When two pipes fill a pool together, they can finish in 5 hours. If one of the pipes fills half the pool then the other takes over and finishes filling the pool, it will take them 18 hours. How long will it take each pipe to fill the pool if it were working alone?

Answer 1

Answer:

Step-by-step explanation:

Pipe A fills 1/x of the pool per hour, and Pipe B fills 1/y of the pool per hour. In other words, A takes x hours to fill the pool and B takes y hours to fill the pool.

together, they fill 1/x + 1/y of the pool per hour. So, 5 hours times that rate should equal 1 full pool, since together they take 5 hours to fill the pool. That gives you your first equation:

5(1/x + 1/y) = 1

So, Pipe A, working for t hours, fills half the pool:

 t(1/x) = 1/2

 And Pipe B, working for 18 - t hours, fills half the pool:

 (18-t)(1/y) = 1/2

Now this question is changed to system with 3 variables.

I hope you can solve the question now.