M07-25

Another approach: It can be useful to learn how to be flexible with percent questions. In this case, 25 percent of 80 can be thought of as one-fourth of 80, or 20, easily enough. Then, rather than take something like 0.6 * 160 to get the female customers in April, you can work with 10 percent and multiply the result. 10 percent of any number is that number with the decimal pushed one place to the left. Thus, 10 percent of 160 is 16.0, or just 16. 60 percent can be thought of as six 10 percents, or 6 * (16): 96. Using 20 as the basis for comparison, measuring the growth from 20 to 96 does not require anything more than a cursory glance at the answer choices. Why? Because 100 percent of 20 is 20, and 100 percent more than 20 would thus be 20 + 20, or 40, not even close to the target of 96. Eliminate choices (A) through (C).

If a 100-percent increase is 20 and gets us to 40, then
another 100-percent increase will add 20 more and get us to 60, still too low, and
another 100-percent increase will add 20 more and get us to 80, still too low

You can therefore eliminate choice (D), since a 300-percent increase still leaves us 16 short of 96, which means that only (E) can be the answer. If we were to go up another 100 percent, we would get 80 + 20, or 100, slightly above the target. Nothing else is even close. This is a good question on which to practice breaking down numbers by 10 percent. It is quick and easy, and ball-parking the answer and knowing you are right should not be discounted as a test-taking strategy.

Good luck with your studies.

- Andrew

I've revised the question and solution, incorporating additional details for improved clarity. I trust this makes it more comprehensible.