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In a certain office, 50 percent of the employees are college [#permalink]

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07 Dec 2012, 08:16

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24% (02:01) wrong based on 815 sessions

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In a certain office, 50 percent of the employees are college graduates and 60 percent of the employees are over 40 years old. If 30 percent of those over 40 have master's degrees, how many of the employees over 40 have master's degrees?

(1) Exactly 100 of the employees are college graduates. (2) Of the employees 40 years old or less, 25 percent have master's degrees.

In a certain office, 50 percent of the employees are college graduates and 60 percent of the employees are over 40 years old. If 30 percent of those over 40 have master's degrees, how many of the employees over 40 have master's degrees?

Let x be the number of employees in that office. Given that: 0.5x = college graduates; 0.6x = employees over 40; 0.3*0.6x = employees over 40 with master's degrees.

(1) Exactly 100 of the employees are college graduates --> 0.5x=100. We can find the value of x, thus we can determine the value of 0.3*0.6x. Sufficient.

(2) Of the employees 40 years old or less, 25 percent have master's degrees. We have no information about the number of employees in any group, only percentages. Not sufficient.

In a certain office, 50 percent of the employees are college graduates and 60 percent of the employees are over 40 years old. If 30 percent of those over 40 have master's degrees, how many of the employees over 40 have master's degrees?

(1) Exactly 100 of the employees are college graduates

(2) Of the employees forty years old of less, 25 percent have master's degrees

The OA is A.

I agree with the OA if college graduates are in the same group as people with master's degrees. However, in real world, not all college graduates have master's degree. No?

The first statistic (50% of employees are "college graduates") is a red herring. We don't need it to answer the question asked. The final question concerns master's degrees, and we never got any info about the breakdown of degrees held among college grads. We know 60% of employees are over 40, and 30% of those over 40 have a master's degree. So the number of employees over 40 with a master's degree will be 0.3*0.6*(number of employees).

The second statement would be sufficient IF we knew the total number of master's degrees or the total number of employees. But we don't, not unless we use the first statement. The first statement alone is sufficient, whereas the second is not.
_________________

In a certain office, 50 percent of the employees are college graduates and 60 percent of the employees are over 40 years old. If 30 percent of those over 40 have master's degrees, how many of the employees over 40 have master's degrees?

(1) Exactly 100 of the employees are college graduates

(2) Of the employees forty years old of less, 25 percent have master's degrees

The OA is A.

I agree with the OA if college graduates are in the same group as people with master's degrees. However, in real world, not all college graduates have master's degree. No?

Merging similar topics. Please refer to the solutions above.

Re: In a certain office, 50 percent of the employees are college [#permalink]

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01 Aug 2014, 10:47

Hello from the GMAT Club BumpBot!

Thanks to another GMAT Club member, I have just discovered this valuable topic, yet it had no discussion for over a year. I am now bumping it up - doing my job. I think you may find it valuable (esp those replies with Kudos).

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Re: In a certain office, 50 percent of the employees are college [#permalink]

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05 May 2015, 03:48

Hi,

I would like to follow up on the post of linglinrtw, I initially answered the good answer however when re-reading the text, in order to be able to answer the question, we need to make an assumption on the population (it is not either college degree or master degree, it could be something else).

Basically, in many overlapping problems, it is not clearly stated black or white; 1 or 0; and never in the answer this assumption is taken into account.

However, this kind of assuption would be exactly the kind of flaws that the GMAT asks us to find in critical reasoning in the verbal part.

Am I to demanding and should take for granted the assumption in those kind of problem? What do you think? Thanks a lot!

I would like to follow up on the post of linglinrtw, I initially answered the good answer however when re-reading the text, in order to be able to answer the question, we need to make an assumption on the population (it is not either college degree or master degree, it could be something else).

Basically, in many overlapping problems, it is not clearly stated black or white; 1 or 0; and never in the answer this assumption is taken into account.

However, this kind of assuption would be exactly the kind of flaws that the GMAT asks us to find in critical reasoning in the verbal part.

Am I to demanding and should take for granted the assumption in those kind of problem? What do you think? Thanks a lot!

Your doubt is very valid. In fact, in this question, if you try to segregate the groups in a tree structure format and assume that college degree and master's degree are the only two subcategories, you'll see that your inferences would go against the information given in statement 2. (Try it for yourself. Let me know if you need my help in this. )

That essentially indicates that the categories listed out in the question are not exhaustive.

However, the question very clearly asks about the number of employees "Above the age 40 AND having a Master's degree". The percentages given are also exactly relevant to this. (% of employees above 40 and % of master's degree holders among employees above 40)

So the problem essentially boils down to finding the total number of employees in the office itself. In other words, we need not worry about other possible groups among these employees.

In questions where grouping needs to be conveyed very clearly, the GMAT makes sure that the classification is unambiguous. For instance, Red colored balls and Blue colored balls AND Big and small balls among each color. (There is no scope of confusion here because a ball cannot be both Red and Blue at the same time. )

Re: In a certain office, 50 percent of the employees are college [#permalink]

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20 Sep 2015, 04:51

Bunuel wrote:

linglinrtw wrote:

In a certain office, 50 percent of the employees are college graduates and 60 percent of the employees are over 40 years old. If 30 percent of those over 40 have master's degrees, how many of the employees over 40 have master's degrees?

(1) Exactly 100 of the employees are college graduates

(2) Of the employees forty years old of less, 25 percent have master's degrees

The OA is A.

I agree with the OA if college graduates are in the same group as people with master's degrees. However, in real world, not all college graduates have master's degree. No?

Merging similar topics. Please refer to the solutions above.

And finally, please hide OA's under the spoiler. Thank you.

Hi,

Could you help me understand what I am doing wrong here. According to Statement 2, 25% of the 40% of the employees( since 60% are 40 years old) have masters degree and are either 40 or under 40. The question stem tell us that 50% of all employees are college graduates (which the question is assuming is same as masters degree) so why can I not make an equation out of it? (.25)(.4x) + (.3)(.6x)= (.5x)

In a certain office, 50 percent of the employees are college graduates and 60 percent of the employees are over 40 years old. If 30 percent of those over 40 have master's degrees, how many of the employees over 40 have master's degrees?

(1) Exactly 100 of the employees are college graduates

(2) Of the employees forty years old of less, 25 percent have master's degrees

The OA is A.

I agree with the OA if college graduates are in the same group as people with master's degrees. However, in real world, not all college graduates have master's degree. No?

Merging similar topics. Please refer to the solutions above.

And finally, please hide OA's under the spoiler. Thank you.

Hi,

Could you help me understand what I am doing wrong here. According to Statement 2, 25% of the 40% of the employees( since 60% are 40 years old) have masters degree and are either 40 or under 40. The question stem tell us that 50% of all employees are college graduates (which the question is assuming is same as masters degree) so why can I not make an equation out of it? (.25)(.4x) + (.3)(.6x)= (.5x)

Thanks

College graduates and those who have a master degree are not the same group.
_________________

And finally, please hide OA's under the spoiler. Thank you.[/quote]

Hi,

Could you help me understand what I am doing wrong here. According to Statement 2, 25% of the 40% of the employees( since 60% are 40 years old) have masters degree and are either 40 or under 40. The question stem tell us that 50% of all employees are college graduates (which the question is assuming is same as masters degree) so why can I not make an equation out of it? (.25)(.4x) + (.3)(.6x)= (.5x)

Thanks[/quote]

College graduates and those who have a master degree are not the same group.[/quote]

Forget conventional ways of solving math questions. In DS, Variable approach is the easiest and quickest way to find the answer without actually solving the problem. Remember equal number of variables and independent equations ensures a solution.

In a certain office, 50 percent of the employees are college graduates and 60 percent of the employees are over 40 years old. If 30 percent of those over 40 have master's degrees, how many of the employees over 40 have master's degrees?

(1) Exactly 100 of the employees are college graduates. (2) Of the employees 40 years old or less, 25 percent have master's degrees.

Transforming the original condition and the question, we have the 2by2 table that is common in GMAT math test.

Attachment:

GC DS Walkabout In a certain office(20150921).jpg [ 56.35 KiB | Viewed 3577 times ]

From above, we just need to know E and therefore we are dealing with 1 variable. We need 1 equation to match the number of variable and equation. Since there is 1 each in 1) and 2), there is high probability that D is the answer.

In case of 1), 50E=100 gives us E=2, 18E=36. Therefore the condition is sufficient. In case of 2), 40E*25%=10E=x, and we can't find the value for E. Therefore the condition is not sufficient. The answer is A.

Normally for cases where we need 1 more equation, such as original conditions with 1 variable, or 2 variables and 1 equation, or 3 variables and 2 equations, we have 1 equation each in both 1) and 2). Therefore D has a high chance of being the answer, which is why we attempt to solve the question using 1) and 2) separately. Here, there is 59 % chance that D is the answer, while A or B has 38% chance. There is 3% chance that C or E is the answer for the case. Since D is most likely to be the answer according to DS definition, we solve the question assuming D would be our answer hence using 1) and 2) separately. Obviously there may be cases where the answer is A, B, C or E.
_________________

Re: In a certain office, 50 percent of the employees are college [#permalink]

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12 Oct 2016, 12:09

Hello from the GMAT Club BumpBot!

Thanks to another GMAT Club member, I have just discovered this valuable topic, yet it had no discussion for over a year. I am now bumping it up - doing my job. I think you may find it valuable (esp those replies with Kudos).

Want to see all other topics I dig out? Follow me (click follow button on profile). You will receive a summary of all topics I bump in your profile area as well as via email.
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