Lesson: Testing Possible Cases

Comment on Testing Possible Cases

Hi Brent,

Need your help: https://gmatclub.com/forum/if-m-p-s-and-v-are-positive-and-m-p-s-v-which-of-the-following-160298.html

I tried solving it by input-output method and I don't think that's the best approach for it. I chose the following values: m = 3; p = 5; s = 7; v = 2
gmat-admin's picture

Question link: https://gmatclub.com/forum/if-m-p-s-and-v-are-positive-and-m-p-s-v-which...

Yeah, the input-output method MAY help you eliminate some answer choices, but it won't take you all the way to the correct answer.

Here's my full solution: https://gmatclub.com/forum/if-m-p-s-and-v-are-positive-and-m-p-s-v-which...


Hey Brent :) Can you give me your solution to exercise 390 and 176 in the official 2019 guide?
gmat-admin's picture


Hi Brent. I just wanted to say thank you for all these videos and resources. If I had looked at the above linked questions before taking your course, I would have been in shock. But now I am having much much greater success.
gmat-admin's picture

Good to hear!!

Hi Brent,

Please review my solution.

statement 1: xy+y=ODD ; y(x+1)=Odd . This implies y= odd and x+1 = odd. If x+1=odd then x= even.(sufficient)

statement 2: 6x-3y=ODD; 3(2x-y)=odd. We know 3 is odd.(2x-y)=Odd ; x can be even or x can be odd. (Not sufficient)

So, opt A is the correct ans.
gmat-admin's picture

That's a perfectly-reasoned solution. In fact, it's exactly how I'd solve such a question.

That said, if students aren't sure how to proceed with similar questions, they can always just test all possible cases as we have done above.

Add a comment

Office Hours

Have questions about your preparation or an upcoming test? Need help modifying the Study Plan to meet your unique needs? No problem. Just book a Skype meeting with Brent to discuss these and any other questions you may have. 

Change Playback Speed

You have the option of watching the videos at various speeds (25% faster, 50% faster, etc). To change the playback speed, click the settings icon on the right side of the video status bar.

Have a question about this video?

Post your question in the Comment section below, and I’ll answer it as fast as humanly possible.

Free “Question of the Day” emails!