Question: Committees without R and S

Comment on Committees without R and S

Why are you making 4 person committees when it says 3 person committees in the question?
greenlight-admin's picture

Good catch! Funny, you're the first person to point that out. We'll fix that video shortly.

How many possible questions on Counting should be in the GRE test?
greenlight-admin's picture

They aren't that common. On test day, you might see 1 or 2 counting questions.

What should the real answer be with a three person committee? I am getting 25??

greenlight-admin's picture

With a 3 person committee, the answer is 30 (35 possible 3-person committees - 5 committees that break the rule)

Why can't we do 5C3 in the second stage( when we are breaking the rule)? Thank you so much!
greenlight-admin's picture

Good question, Ketan.

I think I understand your rationale for wanting to use 5C3.
You're saying that, if Rani and Sergio cannot be on the same committee, just remove them and select 3 people from Takumi, Uma, Vivek, Walter and Xavier.
We can do this in 5C3 ways.

The problem with that approach is that it doesn't allow for certain outcomes.

The restriction that Rani and Sergio cannot be on the same committee still allows for ONE of them to be on the committee.

For example, an acceptable committee is: Rani, Walter and Xavier
However, your 5C3 approach doesn't allow for that configuration.

Does that help?

Cheers,
Brent

Thanks! I now get it :)

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