Official Solution:


Electrician Magazine surveyed 1,000 electricians who had passed an advanced certification exam. The magazine asked the electricians how many hours they had studied for the exam. It was found that 700 of those who passed had studied for more than 50 hours, and 300 had studied for less than 50 hours. The magazine concluded that the more hours an electrician studied for the exam, the more likely they were to pass.

Which of the following would most strengthen the conclusion of the magazine?


A. Some of the electricians in the survey actually studied more than 100 hours
B. Many of those surveyed thought the exam was unnecessary and did not reflect on their ability as electricians
C. The electricians in the survey all took the exam shortly after reaching five years of experience as an electrician
D. Some of the electricians in the survey had also completed a 24-hour course in electronics
E. About half of the electricians in the survey had college degrees in a variety of fields


(A) This answer choice does not provide further support for the conclusion. It only states that some electricians in the survey studied more than 100 hours, but not how many.

(B) This answer choice is irrelevant to the conclusion.

(C) Correct. If the electricians had different amounts of experience, the key factor in passing the exam could have been experience, not how much they had studied. This answer choice indicates that all of the electricians had similar amounts of experience, and therefore provides support to the conclusion.

(D) This answer choice actually weakens the conclusions. The key factor in passing the exam could be the course, not how much they studied.

(E) This answer choice is irrelevant.


Answer: C
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I am not sure about answer choice B. If exam was not reflective of their ability as electrician, experience/natural skills or any other factor did n't matter leaving only study of exam as most contributing factor.
Could anyone help me understand why B is not the answer?

I think this is a high-quality question.

I think this is a high-quality question and the explanation isn't clear enough, please elaborate.

The Magazine concludes that "the more hours an electrician studied for the exam, the more likely they were to pass". How option C strengthens this conclusion?
How experience is related to the number of hours put in to studies? Other options seem to be wrong as well.

Why not option D?

Assume, some people among 300, who had studied less than 50 hrs, had compensated that amount of time by doing this additional course which implies that indeed studied for the main course.

IMHO that's out of scope the Stimulus talks about electricians , however option (D) talks about electronics...

Let's not forget that Electronics is a different branch of science and may be there is no relation between electronics and electrician's field of study..

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It may so be the case that the more experience one have, the more knowledge he gains in the subject and therefore the less he/she needs to study fro the exam for an equivalent score. Therefore another factor other than studying could have played a role in the difference in the results. Option C confirms that such difference does not exist and all test takers have equivalent experience - in other words apples are compared to apples, not oranges.

Hi bb,

I marked option E. if the electricians have different background in terms of formal education, hence the more they study, the better chance to qualify the exam

You have missed the term "for the exam". Studying something other than that required for the exam is not relevant for this argument.

Damn!!! this question is very good

Answer C, actually acts as a defender, it excludes any other possibilities and factors that could undermine the magazine's conclusion (acting like a shield and strengthens). Hell Yeah !!!

I enjoyed this question very much)) KUDOS to author

Option C should actually weaken the conclusion by giving an alternate reason for passing the exam.
It shows as though 5 yrs of experience was responsible for passing. Instead if the question said " Not all have the same experience ", the conclusion that passing happened due to studying would be strengthened.

Option C makes both the groups (passed and failed) comparable. Option D implies that since all the candidates had the SAME experience, years of experience is NOT the reason for passing the exam - if it were, then the 300 students who studied less than 50 hours would not fail.

If the statement were that not all had the same experience, as you mentioned, then it could NOT be concluded that hours of studying was related to better performance - then the experience could as well be a factor for better performance. But bringing all the candidates at par in terms of experience strengthens the conclusion. The correct option could have been "Not All have the same experience."

(Consider the alternative possible answers: All the candidates were of same age / same IQ. This could also be a possible strengthening statement because then it would be confirmed that age / IQ is not a factor influencing the result.)

so you are saying
Negating any of the probable alternate cause can act as a strengthener ?

The Argument doesn't say that the 300 students failed. It says all the 1000 passed the exam, and out of 1000, 700 studied>50 Hours, and 300 studied <50 Hours. So i agree that C actually weakens the conclusion by giving alternative explanation. Please note, the survey doesn't include the failed candidate, but only passed candidate.

It's really depend what kind of electrical services Singapore you want to become, and where do you want to best in the market of Singapore.

Agree with this, the people who take the survey all passed and all have 5 years experience, suggest that since they all have this much experience they all passed

The question says: The electricians in the survey all took the exam shortly after reaching five years of experience as an electrician.

Option C simply gives another reason why all of those surveyed may have passed; it doesn't say that those who failed also had five years' experience. With option C the magazine's conclusion is weakened, since there is an additional variable that has not been included and may well be a significant reason why those surveyed passed the test. For all we know, those who failed don't have career experience, and that is why they didn't pass.

I think this is a poor-quality question and I don't agree with the explanation. Please see my comment above. Option C provides an additional variable that may well be the reason those surveyed passed the test (making hours studied NOT the reason), which weakens the magazine's conclusion. We have no indication whether or not those who failed also had at exactly five years' experience. Perhaps they all have less, and the correct conclusion is that more experience makes it more likely to pass the test. Perhaps all those who failed had MORE experience, and the conclusion is that more field experience leads to a sense of confidence about the material, and the false confidence leads to failure of the exam.

Or maybe in the end, everyone who took the test, even those who failed, all have five years of experience, and it is hours studied that predicts likelihood of passing. But we can't deduce that with answer C, since we're only given information on those who passed.