anon1 wrote:

Agh on a cold streak

If pipe B fills a container at a constant rate in 100 minutes, how many minutes does it take pipe A, working at is own constant rate, to fill the same container?

(1) Pipe A and pipe B together fill the container at (1/4) the time it takes pipe A alone.

(2) Pipe A and pipe B together fill the container at (3/4) the time it takes pipe B alone.

I initially chose B because stat(1) gives us information that is relative to an unknown (A) So I wasn't sure how this would be sufficient.

agh, anyone have any insight?

For any such question of rate A , rate B and total rate T question remember the relation

1/T = 1/A + 1/B

Now question already gives you B =100

So eventually u have equation

1/T = 1/A + 1/100

And question is asking value of A. Which we can not find because of unknown T.

Now lets look at statements

Statement 1: Together it takes 1/4 time of A. => T = A/4. You just got the relation between A and T. You can surely solve the equation in question with this to get A.

Statement 2: Together it takes 3/4 time of B => T = 3B/4 and you already know B. so you know T. you can again solve the euqation in question with this to get A.

Hence ans D it is !

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