GRE Answer Choice Tricks, Part 1
December 28, 2012
Few things are as unpleasant as that burst of terror you feel when you crunch all the math, get the answer — and it’s not in the choices. Oh no! What did I do wrong! Sometimes, the answer is … nothing! The GRE test makers will deliberately engineer problems to provide that moment of fright: you’ll get the right answer, but it won’t look like the right answer choice.
When this happens, don’t panic. There are a few tricks the test makers use to get your answer to look different from the credited choice. Instead of panicking, just assume that you do have the correct answer, and think back to the tricks. I’ll teach them to you in this post and in the next couple.
Test Maker Trick #1: Have the math work out to a fraction, then ask for a percent.
Sometimes the test makers will give you a bunch of fractions in the problem, but ask for a percent in the choices. For example, let’s say you work out the math and get an answer of:
But the choices are written as percents. What to do?
Well, one option is to pop the fraction into the on-screen calculator and match it up with the right answer. But that’s no fun; calculators are for wimps. Instead, exercise your cleverness and rewrite the fraction out of 100. Percents are out of 100, so any fraction with 100 on the bottom will convert naturally to a percent.
You can do this quickly — even more quickly than a calculator! — if you have the factors of 100 at your command. They are:
1, 2, 4, 5, 10, 20, 25, 50, 100
Play with the fraction to make the denominator one of these numbers, then multiply to reach 100. In this case, 40 is 20 × 2, so:
And now, since 100 = 20 × 5, multiply through the fraction by 5:
Note that while 8.5 × 5 may seem like something you’d need a calculator for, it’s not: eight times five is 40, and five times 0.5 is 2.5, so just add 40 and 2.5 to put the finishing touches on this GRE problem: 42.5%.