IR Explained: Q21: Indigenous Populations

June 1, 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.

This Table Analysis question combines several quantifiable characteristics with several non-quantifiable ones. For 13 indigenous populations, we are given the name of the population, its location, its economic base, and its residence, along with three numbers.

These numbers include market integration (MI), which appears to be scaled between 0 and 100; "percentage participating in world religions" (WR), also between 0 and 100; and average community size (CS), which ranges from 43 to 4,063.

21A turns up a quirk of the table. Since "economic base" can contain multiple descriptions, sorting the column won't help. To isolate foraging populations, as we need to do for this question, we must find them ourselves.

The populations that forage are Au (MI = 1), Hadza (MI = 0), Tsimane (MI = 7), and Yasawa (MI = 21). It is not entirely clear whether Yasawa should be included, since their economic base is "marine foraging," not "foraging," but it doesn't matter to the answer. Either way, all of these MI numbers are below the MI numbers for any other population in the table. 21A is Yes.

21B, by contrast, allows us to take advantage of the sort function. To identify the populations that both farm and work for wages, sort by "economic base," and then note the three relevant groups: Gusii, Isanga Village, and Maragoli.

All three are sedentary, to answer the first part of the question. The five largest populations are easy to spot: They are the only five over 1,000 people. These three populations are among the five, so 21B is Yes.

21C asks us to compare ranges. To calculate range, find the difference between the lowest and highest numbers in a set. Of these 13 populations, the Mean MI varies from as low as 0 to as high as 82, for a range of 82. The Mean WR is as low as 0 and as high as 100, for a range of 100. Thus, the range in MI is less than the range in WR, and 21C is Yes.

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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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