# Fool Me Once GRE Questions

October 31, 2021

Here’s a popular Fool Me Once question/riddle:

If a plane crashes directly on the border of Canada and the United States, in which country should you bury the survivors?

The answer is neither, since it’s not cool to bury survivors. If you’ve already heard that riddle, then you automatically knew the answer. If today is the first time you encountered the riddle, then you’ll undoubtedly know the answer next time you hear it. That’s what makes this a Fool Me Once question.

Fool Me Once (FMO) questions are questions that leave a larger-than-average mental footprint in the part of your mind that houses your mistakes, and the very existence of those footprints significantly reduces the likelihood you’ll repeat the same mistake. There are several GRE questions that can fall in this category. Here’s an example from the Official Guide Big Book:

Quantity A: 2/9 of x

Quantity B: 22% of x

A) Quantity A is greater.

B) Quantity B is greater.

C) The two quantities are equal.

D) The relationship cannot be determined from the information given.

This question features 2 different FMO opportunities.

If you memorized that 2/9 is approximately 22%, then you might (incorrectly) conclude the answer is C.

However, 2/9 = 22.2222...%

So, since 2/9 is greater than 22%, the answer is A, right?

Nope.

Keep in mind that we’re not just comparing 2/9 and 22%; we’re comparing 2/9 of x and 22% of x, which means we also need to consider the value of x.

For example, if x = 0, then Quantity A equals Quantity B.

If x is a positive value, then Quantity A is greater than Quantity B.

If x is a negative value, then Quantity B is greater than Quantity A.