I was wondering if someone could help with this question.

## Sample 275 mba.com

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- anuprajan5
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- [email protected]
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Just count the number of symbols inside the circles -> 20

20/30 = 2/3

20/30 = 2/3

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- anuprajan5
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Theres 2 issues with that - The number inside the circles would be people abobve 30 or that do not have a high school diploma or both, not under 30 or a high school graduate or both.

And your answer is 2/3 but the answer on the website is different - 5/6. (link below)

Regards

Anup

https://www.mba.com/the-gmat/nex-gen/sam ... x?next=yes

- 160 students are > 30 yr old so 140 students are < 30 year old.

- 80 students do not have diploma so 220 have diploma.

If there is no student who is both <30 yr old and has diploma, total number of students who are either <30 yr old or have diploma, or both is 140+220 = 360.

But we know this number is 260, that's because there are 360-260=100 students who satisfy both conditions.

So finally the probability is 100/300 = 1/3.

- anuprajan5
- Master | Next Rank: 500 Posts
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For the 2nd part of your answer, there is an essential error - the people who have no high school diploma is 90.

REgards

Anup

### GMAT/MBA Expert

- Whitney Garner
- GMAT Instructor
**Posts:**273**Joined:**21 Sep 2010**Location:**Raleigh, NC**Thanked**: 154 times**Followed by:**74 members**GMAT Score:**770

Hi anuprajan5!

They have drawn this problem to be confusing!! I actually re-drew this problem to be an overlapping sets matrix, but I can show you that in a sec! We'll start with the algebra:

**"What is the probability of selecting a student UNDER 30, or HS GRAD, or BOTH.**

Let's find the areas that fit these and count the tick marks:

UNDER 30 = NOT in the circle on the left, so the 10 across the top and the 4 in the NO HS only circle.

HS GRAD = NOT in the circle on the right, so the 10 across the top (already counted those though), and the 11 in the left circle only.

BOTH = UNDER 30 + HS GRAD = neither in the circle on the left OR on the right, so those are the 10 across the top, but we already counted those.

Add them up: 10 + 4 + (skip the 10) + 11 + (skip the 10) = 10+4+11 = 25

Each counts for 10, so 250/300 = 25/30 = 5/6 or 5 out of 6!

ALTERNATE METHOD:

Let's build a double set matrix. We use the things that can overlap to label the top left box, and then we use the logical opposites of those for the titles next to them. Since NO HS and 30+ are the overlapping traits, the I'll put NO HS on the top left going across, and 30+ at the top left going down. Then HS would go next to NO HS (then total), and <30 below 30+ (then total).

Now we just fill in:

Overlap = 5 ticks = 50 ppl.

Total NO HS = 9 ticks = 90 ppl

Total 30+ = 16 ticks = 160ppl

Neither = 10 ticks = 100ppl

TOTAL = 300ppl

And now the 1-1.5 minute set-up make the questions a cinch!!

(1) <30, HS Grad, or Both

Add these blocks up: 110+40+100 = 250/300 = 25/30 = 5/6

(2) <30 AND a HS Grad

100/300 = 1/3.

Hope this helps!

Whit

Let's find the areas that fit these and count the tick marks:

UNDER 30 = NOT in the circle on the left, so the 10 across the top and the 4 in the NO HS only circle.

HS GRAD = NOT in the circle on the right, so the 10 across the top (already counted those though), and the 11 in the left circle only.

BOTH = UNDER 30 + HS GRAD = neither in the circle on the left OR on the right, so those are the 10 across the top, but we already counted those.

Add them up: 10 + 4 + (skip the 10) + 11 + (skip the 10) = 10+4+11 = 25

Each counts for 10, so 250/300 = 25/30 = 5/6 or 5 out of 6!

ALTERNATE METHOD:

Let's build a double set matrix. We use the things that can overlap to label the top left box, and then we use the logical opposites of those for the titles next to them. Since NO HS and 30+ are the overlapping traits, the I'll put NO HS on the top left going across, and 30+ at the top left going down. Then HS would go next to NO HS (then total), and <30 below 30+ (then total).

Now we just fill in:

Overlap = 5 ticks = 50 ppl.

Total NO HS = 9 ticks = 90 ppl

Total 30+ = 16 ticks = 160ppl

Neither = 10 ticks = 100ppl

TOTAL = 300ppl

And now the 1-1.5 minute set-up make the questions a cinch!!

(1) <30, HS Grad, or Both

Add these blocks up: 110+40+100 = 250/300 = 25/30 = 5/6

(2) <30 AND a HS Grad

100/300 = 1/3.

Hope this helps!

Whit

Whitney Garner

GMAT Instructor & Instructor Developer

Manhattan Prep

Contributor to Beat The GMAT!

Math is a lot like love - a simple idea that can easily get complicated

GMAT Instructor & Instructor Developer

Manhattan Prep

Contributor to Beat The GMAT!

Math is a lot like love - a simple idea that can easily get complicated

- anuprajan5
- Master | Next Rank: 500 Posts
**Posts:**279**Joined:**25 Jun 2012**Thanked**: 60 times**Followed by:**10 members

You are my princess in white! I should have realized that a venn diagram with 2 paramaters could be drawn into a double matrix.

27 days before I get something that works

Regards

Anup