Electrician Magazine surveyed 1,000 electricians who took an advanced certification exam. Of these 1,000 candidates 500 passed the exam and 500 failed. The magazine asked the electricians how many hours they had studied for the exam. It was found that those who passed had studied on average 50 hours, and those who failed had studied on average 20 hours. The magazine concluded that the more hours one studies, the more likely they are to pass. Which of the following, if true, 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. Many of the electricians who passed had completed a course in electronics covering some of the topics also included in the syllabus of the certification exam. E. Majority of the electricians who failed had college degrees in a variety of fields not related to electrical subjects.

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30 Jul 2025, 19:58

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srik410

I like the solution - it’s helpful. Nice subtle question. FYI, Chatgpt 4o(general purpose model) got this wrong, but o3 model(advanced reasoning), got this right with 90% confidence. Shows that definitely there is something to learn from here.

I found the 4o to be lacking with harder arguments/logic in my research... and the funniest thing I found is ChatGPT 3.0 arguing vs. gemini 2.5 pro and both refusing to budge (I would copy paste replies from one to the other and they would just go deeper and deeper into it)

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Amazing question really. I could clearly see why Option C is correct.

But I was failing to see why option E is wrong. I eventually understood it and then only noticed option D is very similar.

Learned a lot. Great question. Subtle.

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04 Aug 2025, 14:33

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Arunava7393

Thank you for the positive comment.
Few people find it necessary positively comment on a question and I understand that but it is so nice to hear them

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You're teaching me more on Gmatclub forum than I will learn in MBA. The Irony. 🌌

Arunava7393

Thank you for the positive comment.
Few people find it necessary positively comment on a question and I understand that but it is so nice to hear them

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Thank you... but you will be surprised how challenging the application process is vs. taking the GMAT and then how it is a whole different level when you go to business school... not to scare you

Arunava7393

You're teaching me more on Gmatclub forum than I will learn in MBA. The Irony. 🌌

Arunava7393

Thank you for the positive comment.
Few people find it necessary positively comment on a question and I understand that but it is so nice to hear them

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I like the solution - it’s helpful.

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I like the solution - it’s helpful.

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Such an amazing question! I love this one.

I got this wrong for the 2nd time but learned.

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25 Oct 2025, 10:46

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Arunava7393

Such an amazing question! I love this one.

I got this wrong for the 2nd time but learned.

Thank you for giving credit where it is due

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I don’t quite agree with the solution. The question says, no. of hours spent studying varies directly with the likelihood of passing the exam. Option 3, however, emphasises work experience, which is not mentioned at all in the question. Work experience is different from studying. So option 4 should be correct, as taking a course equates to studying.

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14 Nov 2025, 08:39

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bizshraddha

You’re bringing up a good question about scope. A lot of the critical reasoning questions are proven correct or incorrect by going outside of the scope of the argument for example conclusion questions or assumption questions are good examples.

Strengthen and weaken questions however often introduce additional evidence which will therefore strengthen or weaken the argument by either clarifying or adding.

In this case it’s a very weak and soft strengthener especially who tells us that all the electricians had the same amount of work experience and therefore it was an even comparison and you didn’t have somebody with one year and somebody was 15 years of experience.

Answer choice D introduces a course. There are a few gaps in the answer choice. We don’t know when it was completed. We also didn’t know how long it was. And we know that this course overlaps with the certification in a few areas but it doesn’t appear to be a part of the exam preparation curriculum.

This resulted the situation such as one of the course was taken five years ago and it was only a two hour course. In this case it’s completely useless and this is just a coincidence

On the other hand, if this course was done right before the exam and it was a 400 hour course, maybe these people who passed the exam didn’t pass it because they studied for the exam but because they took the course. They did not take this course to study for the exam which is the eventual issue with answer choice D)

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I did not quite understand the solution. I went with D because -
they have done previous coursework -> that means they have invested more hours in comparison to someone who has not done previous coursework.

So passed hours = coursework + hours studying (~50)
failed hours = hours studying only (~20)
This strengthens it.

How is this reasoning wrong?

How i eliminated C
- If all electricians have the same experience in the same thing, that provides equal platform which implies
passed hours = hours studied + 5 yrs exp
failed hours = hours studies + 5 years exp
Which doesn't provide anything additional to any of them to strengthen the claim, and enforces the same things.

Please explain

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Updated on: 18 Nov 2025, 12:38

Originally posted by bb on 18 Nov 2025, 12:37.
Last edited by bb on 18 Nov 2025, 12:38, edited 1 time in total.

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Thank you for the question and sharing your approach! To see if that's a valid approach, we can try to poke some holes in the Answer choice D):

1. They completed a course in Electronics, so they studied 1 hour or 100 hours more than others? We do not know. Also they did not study for the exam, and they just took a course. Can we say they studied for the exam?

2. Someone has taken advanced quant course for 6 months in college 5 years ago and they studied 5 hours of Quant before GMAT and got a high GMAT Quant Score. Someone else studied for 1 month before the GMAT and got a high GMAT Quant Score. For the sake of research, how many hours did the first person study for the GMAT and how many hours did they study for the GMAT? Did the first person study for the GMAT or did they study for the college course? Can we say that the first person having studied minimally is accurately represented by 5 hours or 500 hours and we should combine the 2 of perhaps this is a messy area and we should just disqualify them?

3. As there are many questions and assumptions required, this option becomes more problematic even if you take the position that taking a course is contributing to study hours. In reality it is a distraction and a weakener because it is bringing a new variable.

The Strengthener in this case is a very mild one - it is just telling us that the comparison was fair by eliminating one of the potential distractors. So we are told that all electricians had 5 years of work experience and we have not mixed young and old ones, so the experience was not a factor deciding the outcome.

autemitaque