How to Tackle “Draw a Conclusion” Critical Reasoning Questions

by on October 17th, 2009

This week, we’re going to take a look at how to tackle a particular kind of Critical Reasoning question: Draw A Conclusion.

First, grab your stopwatch and try the below problem; give yourself 2 minutes. It’s a ManhattanGMAT problem but we made sure to mimic the real test when we wrote it. When you’re done, do NOT check your answer or read the solution yet (the answer and explanation are at the end of the article). Continue through the article as written (you’ll understand why later).

Company A, the second-largest supplier of triple blade razors, saw its sales of triple blade razors decrease from 150,000 units in 1983 to 100,000 units in 1986. From 1980 to 1986, Company A steadily decreased the percentage of its marketing budget that it dedicated to promoting those razors from 50% to 30%. During this same six year period, Company B, the leading manufacturer of triple blade razors, consistently spent 60% of its marketing budget on promoting its triple blade razor, while Company C, an up-and-coming competitor in the triple blade razor market, increased the percentage of its marketing budget allocated to promoting its razors to 25%.

Which of the following conclusions is best supported by the information above?

(A) There is a direct relationship between the amount of money that a company spends on marketing its triple blade razors and that company’s sales of its razors.
(B) Company B is the leading manufacturer of triple blade razors because it spends the largest amount of money on the promotion of its razors.
(C) Company C will soon surpass Company A as the second largest supplier of triple blade razors.
(D) Companies A and B supply more than 2/3 of the triple blade razors.
(E) Between 1980 and 1986, Company A consistently dedicated a larger percentage of its marketing budget to the promotion of its triple blade razors than Company C.

Okay, now that you’ve tried the problem and picked your answer, let’s discuss what’s going on here.

First, we’re going to talk about the kinds of answers that are considered “good” by the test writers and the kinds of answers that are considered “bad” by the test writers. After we’ve discussed this, you should return to the problem to see whether you still want to pick the same answer or whether you want to switch answers.

On “Draw a Conclusion” questions, the test writers want us to find the answer choice that must be true according to the given premises (the information in the argument); we should not be able to argue with the correct answer. The test writers are not asking us to infer anything; we are not supposed to draw a conclusion the way we would in the real world.

For example, if I tell you that chocolate is my favorite flavor of ice cream, what might you infer? Perhaps you’d infer that I like chocolate in general, and I also like ice cream in general. Perhaps I like dessert or sweet things in general. These would all be reasonable inferences to make in the real world; they are likely to be true.

They do not, however, definitely have to be true. By definition, “favorite” means “the one that I like the best.” What does have to be true if chocolate is my favorite flavor of ice cream? Vanilla is not my favorite flavor of ice cream. I don’t like vanilla ice cream better than I like chocolate ice cream. I don’t like vanilla ice cream as much as I like chocolate ice cream. Any of these would be acceptable answers for the GMAT test-writers because these things must be true, according to the given premise (that chocolate is my favorite flavor of ice cream).

Now that you know this, go back and take a look at the answers choices again. Do you want to stick with your original answer? Or do you want to pick a different answer?

Okay, let’s pick this problem apart.

The “argument” in a Draw A Conclusion (DC) question typically consists of a series of facts. The word “argument” is in quotes because there usually isn’t a real argument, or major claim, made on a DC question – you can see that if you review the above argument. Our first task is to read the argument and make sure that we understand what we have (and have not) been told.

So, what did this argument tell us? (And what didn’t it tell us?)

We know information about the relative market positioning of the companies. Company B is the #1 company and Company A is the #2 company; Company C is lower down on the list, but we don’t know the exact position.

We know information about the triple blade razor sales of Company A from 1980 (150k) to 1983 (100k). We don’t know sales information for the other two companies.

We also know information about how each of the three companies allocated a percentage of their marketing budgets specifically for triple blade razors over the period 1980 to 1986:

  • Company A steadily decreased from 50% to 30%; the percentage was never higher than 50% or lower than 30% – otherwise, the percentage would have increased at some point rather than “steadily decreased”
  • Company B stayed steady at 60%
  • Company C increased to 25% from some unknown, but lower, starting number (because it increased to 25%)

Now let’s review the answer choices, keeping in mind that we want to find the one that must be true, given the above info.

Answer choice A is very tempting. It does seem like the argument is telling us: hey, if you spend less money on marketing, then your sales are going to suffer! The problem? Answer choice A talks about “the amount of money” but we don’t know anything about the amount of money spent! Did you notice that? The argument discusses only percentages of budgets spent. What if Company A’s marketing budget is $1 million and Company B’s marketing budget is $100,000? Then Company A will have spent more actual money, even though the percentage spent was lower! This doesn’t have to be true. Eliminate A.

Answer choice B is also tempting, but we still don’t know anything about the “amount of money” each company spent. Eliminate B.

Answer choice C tries to make a future prediction. Do future predictions have to come true? No. Eliminate C.

Answer choice D is about the number of razors sold; we only have such data for Company A. We don’t know anything about the number of razors sold by B, or the proportion sold by the two companies together. Eliminate D.

Answer choice E is the correct answer! First, the choice is limited to the time period 1980 to 1986, which is good because the argument only mentions this timeframe. Next, it says that the percentage of budget spent by Company A on triple blade razors was always greater than the percentage spent by Company C. This is true! In the given timeframe, Company A’s percentage was always somewhere between 30% and 50%, inclusive. Company C’s percentage was always 25% or lower.

So, what’s the big lesson to learn here? First, make sure you know what you know and you know what you don’t know. (In particular, watch out for arguments that discuss percentages of money and then leap to discussing actual numbers in the answers. You don’t necessarily know anything about any actual numbers.) Next, look for the answer choice you can prove to be true, based upon the premises. Eliminate anything that doesn’t have to be true!

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