Critical Reasoning

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Critical Reasoning

by RiyaR » Sun Oct 26, 2014 4:39 am
In the past 50 years, the population of honeybees in the United States has been cut in half. The decline is due primarily to the increasing use of pesticides in the United States, as well as to the introduction of two types of mites that weaken and kill the bees. Honeybees are the primary pollinators for a variety of important fruit crops, including oranges, apples, grapes, peaches, cranberries and watermelons. Therefore, if the honey bee population continues this drastic decline, then most fruits will no longer be available to consumers.

In evaluating the conclusion, which of the following questions would be LEAST useful to answer?

A)Are there other insect pollinators that could pollinate these fruit crops instead of the honeybee?

B)Are honeybee populations declining in other important fruit-producing regions, like Chile and New Zealand?

C) Is it feasible for humans to hand-pollinate the fruits that have been pollinated by bees?

D)Will reducing the use of pesticides in the United States reverse the decline in honeybee populations?

E)Is it possible to genetically engineer fruit-producing plants so that they no longer require pollination?

I marked B, but the answer is D.Isnt D necessary to evaluate the argument?

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by [email protected] » Sun Oct 26, 2014 8:13 pm
Hi RiyaR,

This CR question is more "layered" than average and requires you to think about far more details (and possibilities) than you typically will on a CR question. It asks us which of the following questions would be LEAST useful to know the answer to, meaning that 4 of the questions ARE useful and would provide important information to evaluate the prompt.

The logic behind the prompt is a fairly simple set of causal ideas (the idea that X causes Y):
- honeybees are the PRIMARY pollinators for a variety of important fruit crops.
- the population of honeybees has been cut IN HALF by 2 THINGS (IN THE UNITED STATES):
1) increased use of pesticides
2) introduction of two types of mites that weaken/kill the bees.
- if the honeybee population continues to decline, then most fruits will NO LONGER BE AVAILABLE to consumers.

Since we're looking for 4 answers that pose relevant questions about this situation, I'll use the above causal arguments to find answers that address the logic:

1st, honeybees are the PRIMARY pollinators.....maybe there are OTHER ways to pollinate the plants (so we can get around the problem of a decreased honeybee population)...Answers A (other insects), C (humans) and E (genetically introduced plants that don't need pollination) are all relevant issues that would allow us to get those fruits without needing honeybees.

2nd, since this prompt is focused on honeybee problems in the UNITED STATES and how fruit would NO LONGER BE AVAILABLE, we might STILL be able to get fruit ELSEWHERE and not have to deal with this problem at all....Answer B addresses the idea of OTHER important fruit-producing regions. If these other regions produce fruit, then we wouldn't face the issue of the fruit NO LONGER BEING AVAILABLE.

Answer D is tempting, but reducing the pesticides won't necessarily solve the problem. The mites that weaken/kill the bees might still keep the bee population down even the pesticides are removed altogether. Without knowing about BOTH the pesticides AND the mites, we won't be able to evaluate the plan. As such, D is the answer that is least useful.

Final Answer: D

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by David@VeritasPrep » Mon Oct 27, 2014 3:51 pm
So this is a Veritas Prep Question from the Veritas Question Bank. For access to that Question Bank follow the link.

A couple of more facts:

1) I wrote this one! I had not looked at it for a few years but this is one of mine. I combined the logic from two official GMAT problems, one provided the "least useful to know" part and one provided the "limited conclusion" that I will discuss in a moment.

2) This is a really tough question. It is above the 90th percentile. I just looked at the stats and this question actually has a really good profile. So this is a valid question as far as the stats are concerned.

3) More than 50% of people choose "B" as the answer. As of this moment, out of 3454 people who have attempted this question 1855 chose B as the answer. So that is a powerful sucker choice!


I really like what Rich has said above. He gave a very nice explanation for D. It is different than the official explanation but it is a great explanation.


The official explanation: The way that I wrote this question was to focus on the idea of a limited conclusion. This is one of the toughest concepts in critical reasoning because it only applies the conclusion to a limited set of circumstances.

For example, there is a question that says, "In training engineers who will build buildings for industry, we should limit the focus on mathematical principles (because computers do the math these days." Notice that the conclusion only applies to engineers who will work in industry. So physicists still can study lots of math as well as mathematicians! When you see a limitation on a conclusion it is not just an sort of introduction, it is a valuable part of the conclusion.

For this conclusion I marked the limitation in bold "Therefore, if the honey bee population continues this drastic decline, then most fruits will no longer be available to consumers."

Do you see that this conclusion only applies if the honey bee population continues to decline? If the population does not decline then the conclusion just does not apply. It is like me saying to you, "If you ride that motorcycle you put on your helmet." If you do not ride the motorcycle I do not expect you to wear a helmet around all day.

So Choice A, B, C, and E all point out that even if the honeybee population does decline in the U.S. we may still be able to get fruit and that is the point of the conclusion.

Hope that makes sense!
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by David@VeritasPrep » Mon Oct 27, 2014 4:04 pm
I forgot to include the link to the question bank where this question is found.

Here is the link https://www.veritasprep.com/gmat-question-bank/

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