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Just encountered this now. I knew how to approach it but what confuses me is that the problem doesn't ask for DISTINCT prime numbers. It just asks "how many prime numbers". So I answered five but apparently, the answer is four? What tells you guys it's asking for distinct numbers?

by boysangur

Fri Sep 03, 2010 8:38 pm
Forum: Problem Solving
Topic: how many prime numbers between 1 and 100
Replies: 13
Views: 12828

This is a question I just messed up on. The way I figured was that Harry needed NOT to be selected for the position of president out of 10 people (probability 9/10), AND (x) be selected as the SECRETARY (1/9) OR (+) TREASURER (1/8). So what i ended up with was 9/10 x (1/9 + 1/8). I know this answer ...

by boysangur

Sat Aug 28, 2010 1:47 pm
Forum: Problem Solving
Topic: A certain club has 10 members-including Harry.
Replies: 26
Views: 21325

Thanks for this discussion people. This question has literally been driving me nuts. On a test (even a practice test) where wording seems to be so important, a question like this can really mess with you. He got 20 cards in a box, then he picks cards "randomly". How does he ensure he draws...

by boysangur

Fri Aug 27, 2010 1:45 pm
Forum: Problem Solving
Topic: Hard number problem - princeton bin 4
Replies: 12
Views: 5814

Thanks a LOT for posting this. I'm going through Kaplan right now and these types of problems are kicking my butt. I could never fully wrap my head around these problems, I don't know why. More on topic: has anyone looked at #24? In the answers, it says that the probability of choosing an even numbe...

by boysangur

Sun Aug 15, 2010 12:25 pm
Forum: GMAT Math
Topic: Probability and Combination Problems
Replies: 16
Views: 50233