Permutation, Combination and Probability

[matt.lopz]

Guys,

I was wondering how should I prepare for Permutation, Combination and Probability type problems. I have read articles from guys who have scored above 700 that they have not faced more than 1 question in the actual test.

Is it worth devoting time to absorb all the concepts on Permutation, Combination and Probability? Are the concepts covered in MGMAT gudes sifficient for actual GMAT exam?

[papgust]

I believe you must at least learn the basics of the two topics. Even my weak areas were these two and for the past 2 weeks, i learnt the fundamentals and practiced many easy problems and medium-level problems. Now i feel much comfortable with these 2 topics. Better NOT to ignore these 2 topics! I've heard from a guy who has got 3-4 problems in these 2 topics on his actual GMAT

[matt.lopz]

Is solving the MGMAT Permutation, Combination and Probability topics and their unsolved exercises sufficient?


Do I need to grasp concepts on circular arrangement, binomial theorem?


MGMAT Instructors, please respond.

[StaceyKoprince]

Most people get just one question total on these topics, so it's not worth a great deal of your time. At most, you might get 2, and there's a good chance one of those will be experimental.

(Beware of listening to what a student said s/he got on the test - people think they get more than they actually did, because they hate these topics. For example, I had a student tell me once that he had 5-6 questions in these areas on his last MGMAT practice test; I knew this was impossible because we limit the number that can be asked. So we looked up his test, and I showed him that he'd had only 2. It's like thinking that you're always in the slow lane during the traffic jam, even though you're not. :)

The other thing about these kinds of questions is that they are a seriously big danger in terms of killing your time - people don't notice when they spend 5+ minutes on these kinds of questions.

So, do know the basics (what's in your book is plenty) and, if you feel like you "get" these, then also know the more advanced stuff discussed in the book. Also learn how to make educated guesses on these. If you happen to get an easier / medium one, you can answer it. If you happen to get a ridiculously hard one, make an educated guess and move on without losing time. You can afford to do this because (a) if it's really hard, then getting it wrong won't hurt your score anyway, and (b) if you even get any really hard ones on the test, you probably won't get more than one.

[matt.lopz]

Thank you so much for your reply Stacey. I am assuming from your reply that student will get only 1 or max. 2 questions per test even though he is in the 750 to 800 scoring range. Is my assumption correct?


Matt

[StaceyKoprince]

yes, even at the highest levels. The last time I took the exam, I got a 770, and I had one probability and zero combinatorics. :)

[matt.lopz]

You are awesome. Thanks a lot for your reply.

[jeromecukier]

Hi. I passed the test today, got a 750 and at least 3 questions on this field. I didn't expect that kind of question and lost a lot of time on them. They were not that difficult but I guess I panicked. such questions involve calculations, in 2 cases I made a stupid mistake early on and wasn't able to find my results in the answers, or the cause of my error. maybe it's bad luck, but this can happen!

[tomslawsky]

For some GREAT explanation and practice, I have to recommend "Ace the GMAT" by Brandon Royal. There are 15 questions and clear explanations in the probability section. The questions are really excellent- the best and least superfluous GMAT treatment of this subject. The book isn't very popular, almost no one refers to it as a resource. It is 40 bucks, but if you're parsimoneus (or broke, like me :), you can track it down in inter-library loan. The book has ~200 problems total split between verbal and quant, but the problems seem quality and the explinations are great. OK, if forgive the typos, that is.

[StaceyKoprince]

Thanks for the suggestion, Tom.

Jerome, it's likely that at least one of those was an experimental question. It may also be the case that, because you don't like those and were hoping not to get them, you actually remember getting more than you did. I had a student once tell me that he got something like 4 or 5 on his last MGMAT practice test. He and I went to look at his test together and he'd only had 2 or 3. His memory literally exaggerated (or maybe he mis-identified some in the heat of the moment). That happens to all of us with things that we don't like.

On a more important note, you got a 750! That's fantastic - congratulations! :)

[matt.lopz]

Stacey and Jerome

Thank you for your replies.

MattL

[pwrbrker2000]

I only had one permutation problem, and it wasn't even a multi-level difficult one. it was pretty easy. I spent way too much time studying for them.

[StaceyKoprince]

Yeah, people stress over these categories too much, but you're going to get a lot more in the areas of Number Properties, Algebra, Stats, fractions / percents... those are more important.