IR Explained: Q20: Exam Scores

May 30, 2012

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This post is part of a series--IR Explained--that walks through the sample Integrated Reasoning questions provided in the latest edition of the GMAT Official Guide.

The passage in this Table Analysis question offers little more than an explanation of the many columns in the large table. You might note a couple of details: that there are 25 students, and that each student's final score was generated using the same weights. They turn out to be important.

20A is one of the more difficult Table Analysis statements you'll ever see. Each student's final score based on his or her three exam scores and generated by some formula, but we don't know the formula. Here we're asked whether the formula weights Exam 2 and the final exam equally.

It's not at all unreasonable to guess on this question to save time. If you read the explanation given on the GMAT's site, you'll certainly come to that conclusion. It is possible to make a reasonable guess, though, without any complex math.

To make an educated guess, look for students with large differences between their Exam 2 and final exam scores. As it turns out, all of the students were within 4 or 5 points between those two exams, so look at those differences. Benson, for instance, got his lowest score on the final. If the three tests were weighted equally, his final score would be above 77; instead, it is below 77. Since his final score was the worst, it is likely that the final is weighted most heavily. The same reasoning, slightly altered, applies to Underhill and Orlando. No counterexamples appear, so the best guess is correct: 20A is No.

Remember the prompt, which told us that each student's score was determined by the same weights? If the prompt didn't tell us that, there would be no way to answer 20A--it wouldn't be established that the weights were consistent at all.

20B is much easier, and it is made more so by the information in the prompt that there are 25 students. To find the median final score (not final exam score!) we need to put the final scores in order and identify the middle one. Use the sort function to get the final scores in ascending order, then count to find the 13th from the top. (Better to know ahead of time that there are 25 students than to waste time counting yourself!) 13th from the top is Orlando, with a final score of 81.50. 20B is Yes.

20C is also more straightforward than 20A. Sort by "Year in Program" to find the 3rd-year students. There are six, and their Exam 1 scores vary from 51 to 91 at the extremes--a range of 40. 20C is Yes.

This Table Analysis example is a great reminder that guessing is always a valid strategy on the GMAT, and Integrated Reasoning is no exception. Many students could spent several minutes trying to puzzle out 20A, and in the end, that time would serve them much better on other, less time-consuming questions.

Stay tuned (or subscribe) for more Integrated Reasoning explanations

 

 

About the author: Jeff Sackmann has written many GMAT preparation books, including the popular Total GMAT Math, Total GMAT Verbal, and GMAT 111. He has also created explanations for problems in The Official Guide, as well as 1,800 practice GMAT math questions.

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