Lesson: Counting Strategies - Part II

Comment on Counting Strategies - Part II

Dear sir,
I m trying to solve all the reinforcement activities. Apart from these from where I should practice the Gre level questions. (Especially counting and data interpretation) Kindly suggest.
greenlight-admin's picture

GRE Prep Club is an excellent source of all GRE questions (official questions and unofficial questions).

Just use their question filter (here https://greprepclub.com/forum/viewforumtags.php) to filter your questions by question type.


Thanks for the help.

Hi, I had difficulty solving this question: https://greprepclub.com/forum/tricky-there-are-n-teams-playing-in-a-basketball-tournam-11153.html. I still couldn't solve it after looking at the solution.

What is the approach in solving this question?

greenlight-admin's picture

This is a crazy hard question.
Here's my full solution: https://greprepclub.com/forum/tricky-there-are-n-teams-playing-in-a-bask...


Hi Brent,

In the Magoosh sample problem with the 7 points on a circle and creating triangles from the points, how is the fact that three verticies next to each other will not form a triangle? Does 7C3 account for that?
greenlight-admin's picture

Question link: https://www.youtube.com/watch?v=OQpybhVoPms

But 3 adjacent points WILL form a triangle.
You may be thinking of counting questions that are set up similarly, but ask you to count the number of DIAGONALS (not triangles).
When counting diagonals, we must recognize that connecting one vertex to an adjacent vertex will not create a diagonal.

Does that help?


Ahh yes, that's what I was thinking. Can you go through the diagonals question again? I've seen it somewhere, but cannot find it. Thanks Brent!


In step3, how did you arrive at the expression for the no. of games won: n * (n-1)(n-9)
greenlight-admin's picture

Question link: https://greprepclub.com/forum/tricky-there-are-n-teams-playing-in-a-bask...

I believe you're referring to pranab01's solution (my solution doesn't involve the variable n).

I'm not sure how pranab01 got that algebraic expression.
It should just be (n-1)(n-9) [note (n)(n-1)(n-9)]
If we continue with pranab01's solution, we see that the n mysteriously disappears!!

Here's my full solution: https://greprepclub.com/forum/tricky-there-are-n-teams-playing-in-a-bask...


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