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A Math question disguised as CR, please solve

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A Math question disguised as CR, please solve

by utkalnayak » Tue Jan 20, 2015 12:07 pm
Super steak house offers three types of steak dinners: Great, Greater, and Greatest. It gets the steaks for the Great and the greater dinners from the nearby Mulberry Meat Market, and the steak for its Greatest dinners are shipped by freight from Omaha on Ice. The prices of its dinners are $25 (Great), $35(Greater) and $40(Greatest). Even after accounting for freight costs, the gross margin on a Greatest Dinner is higher than a Greater Dinner, and twice as high as that of a Great Dinner.

If the above statements are true, which of the following must be true?

A. A great steak can't cost super steak house more than $13.

B. Freight charges do not represent more than 20% of the total cost of Greatest Steak.

C. When taking freight charges into account, a Greater Steak has an identical cost as a Great Steak.

D. A Greatest Steak, exclusive of freight costs, has a higher cost than a Great Steak.

E. If freight charges are less than $6 per steak, a Greatest Steak can cost the same as a Great Steak.
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by VivianKerr » Tue Jan 20, 2015 11:40 pm
The wording of this question makes me wonder what the source is, as it doesn't sound like official or particularly high-quality material. I would NOT recommend studying from a question such as this, as it is not very GMAT-like. Notice how the question uses the word "cost" indiscriminately in the answer choices. It's unclear whether it means the price for the consumer or the cost to the steak house. Are we talking purchase price, or the profits?

That said, I'd classify this as a "MUST BE TRUE" question. We can think of "must be true" questions as the most specific, ironclad inferences. The correct answer can't just be a reasonable inference, it must be ABSOLUTELY true (hence the word "must" in the question-stem!). Don't be tempted to bring in outside, "real world" information. We must accept everything in the paragraph as factual.

Step 1 - Identify the Question-Stem. This is easy for this type of question. The question-stem will contain the phrase "must be true."

Step 2 - Carefully Analyze the Facts. Unlike other types of Critical Reasoning questions, the paragraph won't be an argument so much as a list of facts. Read each sentence slowly then break it down using symbols and abbreviations on your scratch pad. Never copy down the complete sentence. The point is to internalize the given information and put it down in your own words. You won't find a typical Conclusion, so there's no need to write one down. You will also not be required to identify unstated Assumptions.

Step 3 - Predict (if possible). "Must be true" questions are very hard to make predictions for, so unless there's something from the evidence that strikes you as a solid basis for a specific claim, may be forced to move on to the answer choices without a written-down prediction. This means you'll be moving more slowly through the answer choices and will need to examine one with a very critical eye.

Step 4 - Eliminate "sometimes true" or "can be true" options. Some answer choices may be reasonable inferences but will NOT be the correct answer to this "must be true" question. If something "must be true" that means it should be true under ALL circumstances. It cannot only be true occasionally or only under certain circumstances. Always read all five answer choices first then go through them more carefully on the second pass, using process of elimination to eliminate the options that are "obviously" wrong. You'll want to spend the majority of your time and focus on the final two or three options.

Step 5 - Select the choice that HAS to be true. Stuck between two choices? Consider what would happen if the choices were NOT true. Would the evidence fall apart? The choice that has the most negative effect on the evidence in the paragraph when negated is most likely the choice that "must" be true!

Hope this helps get you in the right mindset for this type of problem!
Vivian Kerr
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by utkalnayak » Wed Jan 21, 2015 7:52 am
VivianKerr wrote:The wording of this question makes me wonder what the source is, as it doesn't sound like official or particularly high-quality material. I would NOT recommend studying from a question such as this, as it is not very GMAT-like. Notice how the question uses the word "cost" indiscriminately in the answer choices. It's unclear whether it means the price for the consumer or the cost to the steak house. Are we talking purchase price, or the profits?

That said, I'd classify this as a "MUST BE TRUE" question. We can think of "must be true" questions as the most specific, ironclad inferences. The correct answer can't just be a reasonable inference, it must be ABSOLUTELY true (hence the word "must" in the question-stem!). Don't be tempted to bring in outside, "real world" information. We must accept everything in the paragraph as factual.

Step 1 - Identify the Question-Stem. This is easy for this type of question. The question-stem will contain the phrase "must be true."

Step 2 - Carefully Analyze the Facts. Unlike other types of Critical Reasoning questions, the paragraph won't be an argument so much as a list of facts. Read each sentence slowly then break it down using symbols and abbreviations on your scratch pad. Never copy down the complete sentence. The point is to internalize the given information and put it down in your own words. You won't find a typical Conclusion, so there's no need to write one down. You will also not be required to identify unstated Assumptions.

Step 3 - Predict (if possible). "Must be true" questions are very hard to make predictions for, so unless there's something from the evidence that strikes you as a solid basis for a specific claim, may be forced to move on to the answer choices without a written-down prediction. This means you'll be moving more slowly through the answer choices and will need to examine one with a very critical eye.

Step 4 - Eliminate "sometimes true" or "can be true" options. Some answer choices may be reasonable inferences but will NOT be the correct answer to this "must be true" question. If something "must be true" that means it should be true under ALL circumstances. It cannot only be true occasionally or only under certain circumstances. Always read all five answer choices first then go through them more carefully on the second pass, using process of elimination to eliminate the options that are "obviously" wrong. You'll want to spend the majority of your time and focus on the final two or three options.

Step 5 - Select the choice that HAS to be true. Stuck between two choices? Consider what would happen if the choices were NOT true. Would the evidence fall apart? The choice that has the most negative effect on the evidence in the paragraph when negated is most likely the choice that "must" be true!

Hope this helps get you in the right mindset for this type of problem!
I am glad you think the same. I got confused with the same issue - what does cost mean, cost to the restaurant or cost to the guest. But now I feel okay that official gmat would not ask this. This is a question from 800score practice tests.

My other part of the doubt is that should we expect such data sufficiency type questions as part of CR, the calculation involves time, which might not be adequately planned when one is taking a verbal section of the test.

Thank you.
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by ceilidh.erickson » Tue Jan 27, 2015 11:11 am
I agree with Vivian - this is NOT a GMAT-like question at all. Here are some additional reasons:

- are freight costs and purchase price the only costs we need to consider? What about taxes? Cost differences in prepping the steaks (do we need to hire different chefs, use different oven times)? There is way too much left unanswered.

- while inference CR questions will sometimes ask you to draw mathematical inferences, it's highly unlikely that they would make you do this much calculating with each answer choice.

- the GMAT will never use contractions like "can't"

- "has an identical cost as" is not even idiomatically correct English!

I highly recommend that you stop studying from this source.
Ceilidh Erickson
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Harvard Graduate School of Education
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by VivianKerr » Sat Jan 31, 2015 9:11 pm
Just to answer the specific question you posed, you will NOT be asked to do ANY math calculation in CR. Even questions that involve percents and numbers will be LOGIC based, and no crunching numbers will be necessary. In fact, if you find yourself doing too much math, you're probably missing the entire point of the question. That said, that doesn't mean you can't bring your Quant skills to bear on some CR problems.

Let's look at this sample question from the GMAT Prep 3 exam. It's a classic example of how we must read carefully to determine what percentage or numbers are being discussed:

Fact: Asthma, a bronchial condition, is much less common ailment than hay fever, an allergic inflammation of the nasal passages.

Fact: Over 95 percent of people who have asthma also suffer from hay fever.

These two facts are almost like a math word problem. We can organize the information using a Venn diagram, just like we would in a Math problem. Let's imagine there are 96% of people with asthma who also have hay fever, and 100 people have asthma. Then 96 would also have hay fever and 4 would only have hay fever. Since the first fact tells us that asthma is less common, then we can expect the total number of people with hay fever to be more than 100. Let's say 102 people have hay fever. Our Venn might look like this:

Image

Now we're in a good position to analyze the question-stem and answer choices:

If the information given as facts above is true, which of the following must also be true?

A. Hay fever is a prerequisite for the development of asthma
B. Asthma is a prerequisite for the development of hay fever
C. Those who have neither hay fever nor asthma comprise less than 5 percent of the total population
D. The number of people who have both of these ailments is greater than the number of people who have only one of them
E. The percentage of people suffering from hay fever who also have asthma is lower than 95 percent.

With the sample numbers we picked, there would be 96/102 = 94.1% of people with hay fever who also suffer from asthma. The percentage will always be lower than 95 percent. The only inference we can make is (E).

Takeaway: Quant knowledge on CR can be helpful in certain specific questions, but is NOT a requirement.
Vivian Kerr
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