Cant work this one out - any ideas?

[gmatnovice]

Data Sufficiency

Please determine whether the data provided by the statement s are sufficient to answer the question.

Working together but independently, Scott and Eric can address X envelopes in 18 hours. How long would it take Scott working alone to address X envelopes?

1. In M minutes, Scott addresses three times as many envelopes as Eric addresses in M minutes.
2. Eric can address X envelopes in 72 hours.

* If statement (1) BY ITSELF is sufficient to answer the question, but statement (2) by itself is not;
* If statement (2) BY ITSELF is sufficient to answer the question, but statement (1) by itself is not;
* If statement (1) and (2) TAKEN TOGETHER are sufficient to answer the question, even though NEITHER statement BY ITSELF is sufficient;
* If EITHER statement BY ITSELF is sufficient to answer the question;
* If statement (1) and (2) TAKEN TOGETHER are NOT sufficient to answer the question, requiring more data pertaining to the problem.



not sure how to approach this one

[Alara533]

I went by this method.

(I) says that - In M minutes, Scott addresses three times as many envelopes as Eric addresses in M minutes. this means Scott is 3 times faster than Eric.

Suppose in the 18th minute Eric addressed L envelopes, then Scott would have addressed 3L envelopes.

We have 3L + L = X, ie. L=X/4

Since Scott did 3L envelopes in 18 hours, which is also 3(X/4) envelopes in 18 hours, he would take X = 18 * 4/3, i.e 24 hours if he had to complete it alone!!

Hence Sufficient

(II) Says Eric can address X envelopes in 72 hours. Now lets assume the Scott can complete X letters in Y hours.

Now from the main statement we have - 'Working together but independently, Scott and Eric can address X envelopes in 18 hours'

(1/72) + 1/Y = 1/18, and solving this we get Y= 24!

Hence Sufficient.

So answer should be D.

[Karen]

Shouldn't this be over in the math area?