swerve wrote:If Bob, working alone, can paint a certain room in 3 hours, how long does it take Bob and Richard working together to paint the room?

1) Richard, working alone, can paint the room in 2 hours.
2) Richard paints at a constant rate that is 50% greater than the rate at which Bob paints.

The OA is D

Source: Manhattan Prep

There's a typo in Statement 1. It should be Richard for Bob.

Now let's switch to the question.

We know that the rate of Bob; if we also know the rate of Rich, we can get the answer.

Question rephrased: In how many hours Richard, working alone, can paint the room?

1) Richard, working alone, can paint the room in 2 hours.

This answers the question. Sufficient.

2) Richard paints at a constant rate that is 50% greater than the rate at which Bob paints.

=> Richard's rate = 50% grater than Bob's = 150% of Bob's = 1.5*1/3 = 1/2

=> Richard, working alone, can paint the room in 2 hours.

This is the same as Statement 1. Sufficient.

The correct answer: D

Hope this helps!

-Jay
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