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#14 - Morris High School has introduced a policy designed to

LustingFor!L
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Can you explain answer choices A, B, and C? I correctly chose C, because I didn't think the "before the new policy" language was necessary when attaching the conclusion.
Kristina Moen
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Hi LustingFor!L (I love your username!),

This is a classic numbers and percentages question. The premise tells us about percentages, and the conclusion tells us about numbers.

The premise: "As a result of this policy, only one-quarter of all part-lime teachers now quit during their first year. However, a third of all full-time teachers now quit during their first year."

The conclusion: "More full-time than part-time teachers at Morris now quit during their first year."

This is a common argument flaw. Percentages =/= numbers. If I say that I have 50% of my discretionary income in my pocket right now, do you know how much money is in my pocket? Nope! Because you don't know my discretionary income. So you can't say that I have more money in my pocket than Joe down the street.

This is a Weaken question. We want something that weakens the conclusion. The conclusion is a comparison between full-time and part-time teachers and is talking about the current state of affairs. The premise tells us the percentages now, and the conclusion is about numbers now. Thus, answer choices (A) and (B) will not weaken (or strengthen!) the conclusion. We don't care what teachers used to do. So you are correct that what happened "before the new policy" does nothing to attack the conclusion.

Answer choice (C), (D), and (E) are similar. So what's the difference? Let's look at some sample numbers.
Premise: Part-time teachers: 1/4 quit
Premise: Full-time teachers: 1/3 quit
Conclusion: More full-time teachers quit than part-time.

Answer choice (E): Morris High School employs the same number of new part-time as new full-time teachers.
Okay, if there are 12 part-time and full-time teachers, then 4 full-time and 3 part-time teachers quit. Conclusion still stands. This is not the correct answer.

Answer choice (D): Morris High School employs more new part-time teachers than new full-time teachers.
On the extreme end, what if there are 50 part-time teachers are 3 full-time teachers? Then more part-time teachers quit. Remember, this is a WEAKEN question. So this answer choice weakens the conclusion. It doesn't give us the numbers, but it plants the possibility that there could be more part-time teachers quitting. This is the correct answer choice.

Answer choice (C): Morris High School employs more new full-time teachers than new part-time teachers. On the extreme end, what if there are 4 part-time teachers and 50 full-time teachers? Then more full-time teachers quit. This strengthens the conclusion. This is not the correct answer.

Hope this helps!