OG: In a poll, 200 subscribers to Financial Magazine X indicated which of five specific companies

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OG2021PS137.png
In a poll, 200 subscribers to Financial Magazine X indicated which of five specific companies they own stock in. The results are shown in the table above. If 15 of the 200 own stock in both IBM and AT&T, how many of those polled own stock in neither company?

A. 63
B. 93
C. 107
D. 122
E. 137

E

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AbeNeedsAnswers wrote:
Fri Jun 05, 2020 6:26 pm
OG2021PS137.png

In a poll, 200 subscribers to Financial Magazine X indicated which of five specific companies they own stock in. The results are shown in the table above. If 15 of the 200 own stock in both IBM and AT&T, how many of those polled own stock in neither company?

A. 63
B. 93
C. 107
D. 122
E. 137

E
Another approach is to use the Double Matrix Method. This technique can be used for questions featuring a population in which each member has two characteristics associated with it (aka overlapping sets questions).
Here, we have a population of 200 magazine subscribers and the two characteristics we need to focus on are:
- owns stock in IBM or does not own stocks in IBM
- owns stock in AT&T or does not own stocks in AT&T

So we can set up our diagram as follows:
Image


If 30 of the 200 subscribers own stock in AT&T, then the other 170 subscribers do NOT own stock in AT&T
If 48 of the 200 subscribers own stock in IBM, then the other 152 subscribers do NOT own stock in IBM
When we add this to our diagram we get the following:
Image


At this point, we can complete the rest of our diagram:
Image

Since the bottom-right square represents subscribers who own stock in neither company, the correct answer is E

Aside: We can also use Venn diagrams and formulae to solve overlapping sets questions. However, as difficulty levels increase, it becomes harder to apply those other approaches, whereas the Double Matrix Method works every time.

This question type is VERY COMMON on the GMAT, so be sure to master the technique.

To learn more about the Double Matrix Method, watch this video: https://www.gmatprepnow.com/module/gmat- ... ems?id=919

Once you’re familiar with this technique, you can attempt these additional practice questions:

Easy Problem Solving questions
- https://www.beatthegmat.com/finance-majo ... 67425.html

Medium Problem Solving questions
- https://www.gmatprepnow.com/module/gmat- ... /video/920
- https://www.beatthegmat.com/posted-speed ... 72374.html
- https://www.beatthegmat.com/motel-t271938.html
- https://www.beatthegmat.com/of-the-appli ... 70255.html
- https://www.beatthegmat.com/opening-nigh ... 64869.html
- https://www.beatthegmat.com/at-least-100 ... 74669.html
- https://www.beatthegmat.com/prblem-solving-t279424.html

Difficult Problem Solving questions
- https://www.gmatprepnow.com/module/gmat- ... /video/946
- https://www.beatthegmat.com/ratio-problem-t268339.html
- https://www.beatthegmat.com/overlapping- ... 65223.html
- https://www.beatthegmat.com/fractions-t264254.html
- https://www.beatthegmat.com/overlapping- ... 64092.html
- https://www.beatthegmat.com/mba/2011/05/ ... question-2

Easy Data Sufficiency questions
- https://www.gmatprepnow.com/module/gmat- ... /video/943
- https://www.beatthegmat.com/for-what-per ... 70596.html
- https://www.beatthegmat.com/ds-quest-t187706.html

Medium Data Sufficiency questions
- https://www.beatthegmat.com/sets-matrix-ds-t271914.html
- https://www.beatthegmat.com/each-of-peop ... 71375.html
- https://www.beatthegmat.com/a-manufacturer-t270331.html
- https://www.beatthegmat.com/in-costume-f ... 69355.html
- https://www.beatthegmat.com/mba/2011/05/ ... question-1

Difficult Data Sufficiency questions
- https://youtu.be/dsCeqF9Kbk8
- https://www.beatthegmat.com/double-set-m ... 71423.html
- https://youtu.be/dOZ9KM1m5Hs
- https://www.beatthegmat.com/sets-t269449.html
- https://www.beatthegmat.com/mba/2011/05/ ... question-3

Cheers,
Brent
Brent Hanneson - Creator of GMATPrepNow.com
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n(IBM) = 48
n(AT & T) = 30
n(IBM nAT & T) = 15

Total subscribers = 200

n(IBM) U n(AT & T) = n(IBM) + n(AT & T) - n(IBM n AT & T)
n(IBM) U n(AT & T) = 48 + 30 - 15 = 63

Number of polled subscribers who own stock in neither company = 200 - 63 = 137

Answer = E

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AbeNeedsAnswers wrote:
Fri Jun 05, 2020 6:26 pm
OG2021PS137.png

In a poll, 200 subscribers to Financial Magazine X indicated which of five specific companies they own stock in. The results are shown in the table above. If 15 of the 200 own stock in both IBM and AT&T, how many of those polled own stock in neither company?

A. 63
B. 93
C. 107
D. 122
E. 137

E
Solution:

Since 30 + 48 - 15 = 63, then the total number of people who own stock in either AT&T or IBM is 63. Since we know there are 200 people in the survey, we know that 200 - 63 = 137 people DO NOT own stock in either company.

Answer: E

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