P: X–most–BP: ?C: X–most–C

beth10100 October 7, 2016

Why?

This one doesn't make sense to me. Why would the premise be not B-> not C? That wouldn't be the quickest way to arrive at the conclusion, would it?

Replies

Create a free account to read and take part in forum discussions.

Already have an account? log in

Mehran October 18, 2016

@beth10100 the correct answer here is (A), i.e. not C ==> not B.

The contrapositive of (A) is: B ==> C

This can be combined with our existing premise as follows:

X-most-B ==> C

To conclude:

X-most-C

Hope this helps! For a more in-depth discussion of these concepts, please watch our video lesson on Quantifiers.

ninapogorzelski April 9, 2018

I didn't understand this one either. I still don't understand the thought process.

ldrumm11 April 16, 2018

I don't get this one either...I diagrammed this by writing out 3 X's and above the X's showing 4 C's and below the X's showing 5 B's so not all B's are necessarily C's so why wouldn't it be B-some-C ?

zackliu0830 October 10, 2018

This answer explanation seems wrong. Shouldn't it be X-most-B == > C?

Mehran October 12, 2018

Yes, it is X-most-B ==> C. That is what appears in the message above as well as in the answer explanation.

Are you seeing something different?

Lucas November 27, 2019

Yes that makes sense. Totally forget the combination rules of sufficient and necessary

Lucas November 27, 2019

If it's 2 most statements with the similar variable on the sufficient side, you can combine them.