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## Comment on

3-Criteria Venn Diagrams## Hi,

Can someone explain the formula for three overlapping sets? i don't get it since the video seems to be exhaustive enough to tackle 3 overlapping sets:

Total = Group1 + Group 2 + Group 3 - (sum of 2-group overlaps) - 2*(all three) + Neither

Thx in advance,

Ben

## I've never been a fan of

I've never been a fan of formulas for 3 overlapping sets, and I doubt that the test-makers would create a question that relied on a student memorizing the formula.

Actually, I should say formulaS. There are two:

#1) Total = Group 1 + Group 2 + Group 3 - (sum of all 2 or more overlaps) + (in all 3 groups) + none.

#2) Total = Group 1 + Group 2 + Group 3 - (sum of members in EXACTLY 2 groups) - 2(All three groups) + none

You are using a formula that incorrectly combines formula #1 and formula #2

In this question, we need to use formula #1

We get: 100 = 40 + 60 + 80 - (7 + 46 + 36) + 6 + none

Simplify: 100 = 97 + none

So, none = 3

## Hey Bret, with this concept i

## That's a VERY tricky question

That's a VERY tricky question.

ceilidh.erickson provides a nice solution here: http://www.beatthegmat.com/plz-explain-official-guide-ps-q-178-t281640.html

Her response is the 2nd one listed in the thread.

## i donno about you Brent but

## This is not a common question

This is not a common question type on the GMAT, and I think most students will not see one on test day.

They can be quite time-consuming, so if you're behind time-wise, it's a GREAT candidate for guessing and moving on.

## I guess Bennaghmouch is

x-z+z+y-z+n=total

@ alicia for me the algebraic approach was the easiest one

## Can you please explain this

Of the 300 subjects who participated in an experiment using virtual-reality therapy to reduce their fear of heights, 40 percent experienced sweaty palms, 30 percent experienced vomiting, and 75 percent experienced dizziness. If all of the subjects experienced at least one of these effects and 35 percent of the subjects experienced exactly two of these effects, how many of the subjects experienced only one of these effects?

A. 105

B. 125

C. 130

D. 180

## Hi santhosh1989,

Hi santhosh1989,

ceilidh.erickson provides a nice solution (using a Venn diagram) here: http://www.beatthegmat.com/plz-explain-official-guide-ps-q-178-t281640.html

Cheers,

Brent

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