Problem Solving

AndreaV424 wrote: A. 2 minutes and 44 seconds
B. 2 minutes and 58 seconds
C. 3 minutes and 10 seconds
D. 3 minutes and 26 seconds
E. 4 minutes and 15 seconds

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I calculated that the following

Steven can mix 4 drinks per min
Sue can mix 2 drinks per min
Jack can mix 4/3 drinks per min

Together they make 22/3 or 7 1/3 drinks per minute

I am stuck between answer A and B. How can I calculate the correct second? Should I convert into seconds (see how many second 1 drink takes to make)?

The correct answer is A. I appreciate any help and clarification. Thank you!

There are some good solutions above, so I'll just add a couple of comments:

-you correctly arrived at their rate per minute - they make 7 1/3 drinks each minute. If at this stage you were stuck, you could at least make an estimate:

* after 1 minute, they will have made 7 1/3 drinks
* after 2 minutes, they will have made 14 2/3 drinks
* after 3 minutes, they will have made 22 drinks

So it must take them less than 3 minutes to make 20 drinks, and it certainly doesn't take them 2m58 seconds to make exactly 20 drinks, because that would mean they make 2 drinks in the 2 seconds between 2m58s and 3m00s. There's no partial credit on the GMAT, but if you get partway through a problem, and you're confident your work is correct, you may be able to use that work to at least eliminate some wrong answers, or in this question, pick the correct answer.

That said, I don't care for the question. As a few people established above, the answer is 30/11 minutes. That isn't 2m44s; it's 2m43.6363... seconds. In any real GMAT question, if the answers are rounded off, or are approximations, the question will say as much. Where is the question from?