Combinations/Permutations/Probability: How Frequently Tested

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by Brent@GMATPrepNow » Sun Jul 14, 2013 6:22 am
Since the GMAT is computer adaptive, the number of probability and counting questions you see depends largely on your math skills.
Since probability and counting questions are typically more difficult than other questions, students with strong math skills will see more of these question types than students with weak math skills
Generally speaking, if your math skills are somewhat strong, you should expect to see a total of 1 to 4 probability/counting questions (roughly). If your math skills are somewhat weak, you will see fewer.

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by [email protected] » Sun Jul 14, 2013 11:21 am
Hi Will,

Permutations, Combinations and Probability questions can be some of the toughest questions that you see on the GMAT, although they're not all tough questions (sometimes they're rather straight-forward). As a general rule, you'll likely see 1 of each on Test Day, BUT as you do better and better in the Quant section, the Randomizer is likely to throw you more of them. As such, you could end up seeing up to 3 of each in the Quant section. Make sure that you know the basic concepts, so that you can answer the standard/straight-forward versions of these questions, but don't worry about the crazy versions of these questions (especially if subjects criss-cross, such as a permutation criss-crossing with a probability question).

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by Matt@VeritasPrep » Sun Jul 14, 2013 4:26 pm
Not sure I agree with the previous remarks - it's surprising to see any counting questions in quant these days, irrespective of how well you're doing. Probability does come up, but sparingly (once per exam, I'd say, about as often as standard deviation) - and the probability questions tend to be a little on the hard side, even if you're familiar with the concepts.

As dangerous as it seems, I generally tell students to ignore counting and probability unless they're aiming for a Q49 or higher (for which these days you can't afford to miss more than a few questions). Counting and probability tends to be something most students haven't ever seen, so there aren't even any foggy memories to draw on, and it requires at least as much work as do arithmetic and algebra to answer the harder questions. Arithmetic and algebra, however, are worth the study, as I'd imagine at least 70% of your questions will involve them in some way.