Hi All,

We're told that a certain class, consisting of a lecture and a question-and-answer session, lasted from 2:45 to 4:30 one afternoon and the lecture lasted from 2:45 to 4:15. We're asked for the fraction of the TOTAL time that the question-and-answer session represented. This question is essentially about Arithmetic, but you can take advantage of a math 'shortcut' depending on how you 'see' the information involved.

To start, it's pretty easy to see that the question-and-answer session took 15 minutes (since it lasted from 4:15 to 4:30). Fifteen minutes is 1/4 of 1 hour (since 1 hour = 60 minutes). The total time (from 2:45 to 4:30) can be broken into two 'pieces": the first hour and then the next 45 minutes. That gives us four 15-minute pieces in the first hour and another three 15-minute pieces in the final 45 minutes. That's 4+3 = seven 15-minute pieces, of which the question-and-answer session was one of them. Thus, that sessions is 1/7 of the total time.

Final Answer: A

GMAT assassins aren't born, they're made,
Rich