OG 13TH PS 178 - Video expanation - doubt

[rahul.manhat]

Hello Instructors,

I was reviewing the video explanation of Problem Solving question number 178 (overlapping sets) in the OG 13th.

The video from OG archer explained about dividing the number that is common to all sets by 3 i.e. 105/3. Why would we divide this value(105) by 3 and not by any other divisor.

Could you please explain?

[jlucero]

In the method being explained, the instructor recommends choosing smart numbers to simplify the question. Don't let the dividing by three confuse you- what he is really trying to do is find a number to put in each of the three groups that overlap. In other words, let's just say that there are 35 ppl with (s= sweating, v = vomit, d = dizzy) s & v, 35 ppl with s & d, and 35 ppl with v & d. You could really divide those 105 people up any way that you want. But since there's only one answer to the question being asked, choosing a simple scenario for how many people are in the overlap category allows you to find what the answer MUST be in any scenario. You could just as easily put all 105 people in the overlapping category of s & d and the answer would not change.

[rahul.manhat]

Thank you for the explanation. That really helped!!

[RonPurewal]

great