In this article, we’ll work through a standard GRE Quantitative Comparison question from the ETS Official Guide to demonstrate how estimating can be more efficient than calculating the exact answer. You can either read this article or watch this GMAT sentence correction video on YouTube.
Quantity A Quantity B
54% of 360 150
Let’s begin by writing out the quantities involved in the problem. In this case, we're being asked for 54% of 360.
Before moving forward, it’s critical to translate key phrases to their mathematical counterparts. The term percent, for example, means we have to divide by 100 or shift the decimal left by two places. The word “of,” on the other hand, suggests that we need to multiply. Finally, the words “out of” signify that we need to divide. All of these translations can be harnessed to investigate what quantity A means mathematically. With this in mind, we can see that we're comparing “.54 X 360” to “150.”
To aid the process of elimination, we'll place our four answer choices in between our two quantities. Until you’ve 100% memorized the four options, you can use helper symbols to remember what each answer choice is referring to. With this in mind, you can place a greater than symbol facing Quantity A above choice A, a greater than symbol facing quantity B above choice B, an equal sign above choice C, and “N/A” above choice D.
Rather than using the calculator that the exam provides, estimation will enable us to save valuable time and effort. When percentages are involved, keep in mind that 10% means shifting the decimal left one place, 1% means shifting the decimal left two places, and 50% percent simply means splitting the value in half.
In this case, all we need to do to estimate is divide 360 by two—which gives us the value of 180.
Considering that 180 is less than 54% of 180 and greater than 150, we can confidently select choice B without fully calculating. Note that D can be immediately eliminated if no variables are provided in the quantitative comparison because both quantity A and quantity B gave a certain value.
We hope this example was helpful! To learn more about our online GRE tutoring, visit us here. Learn more about our perspective on tutoring, how we help you identify strengths, weaknesses, build a customized study plan, explain difficult concepts, and more here. Happy studying.