GMAT Integrated Reasoning Strategy

As we noted in this space last week with the unveiling of our new Integrated Reasoning Practice Problems, many students are beginning to prepare for the new section that will become official in June of 2012.  With that in mind, we’ll start to periodically cover some strategic tips for Integrated Reasoning, beginning over the next few months with the strategies that will most help you on the current quant/verbal questions as well.

Today we’d like to cover the first question from Table Analysis Sample #2, linked here.  This question seemingly asks you to calculate huge chunks of data, asking:

Spray bathroom cleaners generated more dollar sales than any other single type of bathroom cleaner in 2010.

To answer this, theoretically you would need to calculate the dollar figures for spray cleaners and every other type of cleaners, but even with a calculator this is a quite time-consuming task.  And don’t let the GMAT’s generosity with the calculator on IR questions fool you – very seldom should you actually use the calculator!  Remember, one foul click and you’ll need to start over – the calculator may be a useful tool in a handful of situations, but don’t let it encourage you to try to “crunch” lists of numbers.

To avoid using the calculator or processing the numbers by hand, consider the “Horse Race” strategy for finding the greatest or least amount in a set of data.  This works not only on an IR question like this, but also on the quant section when questions may ask “which of the following fractions has the greatest value” or something of that type.  The Horse Race strategy notes that you don’t need to know the final score of the winner; you just need to know the winner.  So if you can keep a quick mental tally of who is in front, you may not need to do any math at all.

In this case, a quick sort by “Product Type” should show you that only aerosol and spray cleaners need apply; there aren’t enough powders to even be close in this horse race for the highest total dollar sales.

From there, you can eyeball the differences between sprays and aerosols with a sort by “Dollar Sales.”  The first two spray cleaners earned:

$33.4 million

$27.4 million

And the first two aerosols earned:

$22.3 million

$21.7 million

Pretty clearly, the aerosols have a huge lead – nearly $17 million (11 between the first in each category and 6 between the second in each category).  Your job now isn’t to calculate totals – it’s to determine whether there’s any chance that aerosols make up the $17 million gap.  And it won’t – the third in each category is:

Spray: $16.2 million

Aerosol: $15.4 million

So the gap widens again, and the dollar amounts get smaller – now the total sales of one type of cleaner have  fallen below the overall margin, so unless there are a great many more aerosol sprays in this current sales volume area (and there aren’t), a handful of $1 and $2 million revenue advantages at the low end won’t help.  Sprays are winning in a runaway.

With the horse race strategy, remember that you don’t need to perform calculations – the GMAT is often testing whether you can notice trends or make quick projections without having to do that extra work, but the work is there as a time trap for you if you’re not careful.  As a general rule when analyzing large pools of data, don’t do any math you don’t have to do:

- Note trends

- Round off numbers

- Only deal with the families of numbers that “have a chance” to win

- Go back to conduct further calculation only if it’s needed; chances are, it won’t be

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