Combining methods in GMAT Quant
It’s no secret that there are several strategies for tackling quantitative problems on the GMAT, but you may not have realized that combining methods creates even more options.
Consider the following problem:
A certain school implemented a reading program for its students, with the goal of getting each student to read 2 books per month year-round. If the school has c classes made up of s students in each class, how many books will the entire student body read in one year?
First, notice the variables in the answer choices. That’s a good sign to use the plugging in approach.
We need to choose numbers to plug in for our variables. We’ll choose nice round numbers that make sense. For example, let’s say our imaginary school has 10 classes (c = 10) with 20 students (s = 20) in each class, for a total of 200 students (c × s) .
If each student reads 2 books per month, that’s 400 books per month for the school × 12 months = 4800 books per year. So 4800 is your goal.
At this point, you could plug the values you picked into each answer choice. However, a quick ballpark look at the answer choices shows that (B), (D), and (E) are a fraction of the total number of students. So they will be significantly smaller than our goal.
Now, you can take your time to carefully calculate the values for (A) and (C). Once you’ve eliminated four of the answer choices, you know that the remaining option, (C), is the correct answer.
Once you select a method to start working on a problem, don’t forget to see if you can combine methods for even better results.
Sometimes, using two methods is faster than using just one!
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