GMAT Problem Solving: Tips for Roman Numeral Questions

March 10, 2014
Kaplan GMAT

23647932It’s finally time! You’ve waited all weekend for it, and we’re finally going to share the solution, and more importantly, helpful tips for dealing with GMAT Roman Numeral questions. If you didn’t see Friday’s practice question, take a look now:

GMAT Problem Solving

Roman Numeral Question

If x, y, and z are consecutive odd integers, with x < y < z, then which of the following must be true?

I. x + y is even

II.  is an integer

III. xz is even

  • A) I only
  • B) II only
  • C) III only
  • D) I and II only
  • E) I, II, and III

Strategy and Tips for Solving GMAT Roman Numeral Questions

For Roman Numeral questions, start by finding the statement that appears most often in the answer choices, and evaluate it first. Therefore, if it is untrue, you can eliminate the highest number of answer choices.

In this case, you want to start with statement II.

Next, pick numbers to represent your variables. Since x, y, and z are consecutive odd integers, try x = 3, y = 5, and z = 7. So, (3+7)/(5) = 2, which is an integer. To confirm, try a different set of numbers: x = 7, y = 9, and z = 11. So, (7+11)/(9) = 2, again an integer. Thus, statement II must be true, and your correct answer must contain statement II. So, eliminate choices (A) and (C).

Now consider statement I. If x = 3 and y = 5, x + y = 8. In fact, odd + odd is always even, so statement I must also be true. The correct answer must also contain statement I, so you can also eliminate choice (B).

Are you keeping track of the answer choices you are eliminating on your noteboard? That’s especially important on these Roman Numeral questions!

Finally, in statement III, xz is the product of two odd numbers, which is always odd. Thus, statement III cannot be true, so (D) is the correct choice.


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