Impressed by numbers on GMAT Critical Reasoning

Impressed by Numbers on CR

In GMAT critical reasoning, there are several different types of questions that you will encounter. In this short article, we will cover questions that try to use numbers to throw you off.

Circular Reasoning

One type of fallacy found in GMAT CR questions is getting impressed by numbers. This fallacy is committed when one assumes a data to be good or bad.

Please take a look at the following example:

Example 1: Lily earns more than 90% of citizens in the country. Lily is rich.

Here, “90%” sounds like a very high number, so this data has been assumed to be enough to conclude that Lily is rich. However, this may not be the case. If 90% of the citizens are very poor, Lily could be richer than them and still be poor. Or, if Lily is only slightly richer than these citizens, the first statement would still be true, but Lily would not necessarily be rich.

Let us take a look at another example:

Example 2: Jack improved his score by 200%. Thus, Jack performed well.

Once again, the flaw is that since “200%” sounds like a big number, it has been assumed to be enough to conclude that Jack performed well. However, imagine if Jack’s original score was only 1/100; in this case, after a 200% increase Jack’s score would be 3/100, which may not be enough to say that he performed well.

Let’s take a look at another example:

Examples 3: 98% of its flights are on time; thus, Aster Airlines is among the most punctual airlines in the world.

Once again, “98%” sounds like a big number, but we do not know if it is enough to guarantee that Aster airlines is among the most punctual airlines.

Let us take another example:

Example 4: Only 0.01% of its medicines are defective; Zenith Medicals deserves applause!

Here, 0.01% sounds like a good ration, but as this is medicines, we cannot establish whether this is low enough to justify saying that Zenith Medicals deserves applause.

Let’s now take a GMAT-like example.

Example 5: Brendon, a chess prodigy, earned the status of a Grandmaster at age 15. However, he has only won 30% of his games against other grandmasters; thus, although Brendon is talented, he is among the lesser skilled of the contemporary grandmasters.

Which of the following identifies a flaw in the logical coherence of the argument above?

Here, we have a dialogue followed by a question stem.

Step 1 – Read the question stem.
Step 2 – Read the argument.
Step 3 – Come up with a broad expectation from the correct answer choice.

Please try this yourself before reading on.

The flaw here is in the number “30%”; it sounds like a low number, and therefore a negative conclusion has been drawn about Brendon’s skill level. But, consider that among chess grandmasters many games end in a draw. Thus, we do not know if 30% enough to justify the conclusion.

So, what is the logical flaw here?

Option 1: It bases the conclusion on data for just one player, without considering similar data for other players.

In other words, we do not know how good or bad “30%” actually is in the context of Brendon’s record. This is the correct answer choice.

This article has deliberately been kept brief; for a more elaborate explanation, please refer to the Experts’ Global Stage One Critical Reasoning videos.

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