Timing for challenge problems?

[rchen1987]

If I want a 700+, do I have to be solving these in 2 minutes each?

[JonathanSchneider]

Definitely not. Some of these challenge problems simply cannot be solved in two minutes. They are not real GMAT problems, but rather stuff that we have come up with to test GMAT concepts on a very advanced level. But don't worry about timing on them. Just use them as a good way to practice breaking down very advanced math concepts.

[rchen1987]

Some of these questions are poorly written...

On the 02/24/03 problem, the question clearly asks if the mean > median, and the answer solves for median > mean.

On a prior problem, abc - def could have been interpretted to be a*b*c - d*e*f rather than the numbers themselves...

[StaceyKoprince]

The 24Feb03 problem does not incorrectly solve for median > mean. Based on statement 1, the solution is that the median is always greater than the mean. That's just what it is based on the statement - can't do anything about that. Then, because this is a yes/no question, determining that the median > mean is sufficient to answer the question "is the mean > median?" The answer is a definitive no.

It's important to understand how yes/no DS questions function on the test - they are quite common and can be very tricky.

I'm not sure where the second problem is / when it was published.

ETA: A lot of the challenge problems are harder than anything you'll see on the real test, even if you're scoring in the 99th percentile on quant. So I wouldn't spend time on these unless you were a math major, you're going for a 99th percentile quant score, and/or you really get excited about ridiculously hard math problems. :)