The GMAT is more than just a math or verbal test – it’s a reasoning test. And so it’s important to think not merely about content, but also about the strategy games that the authors of these questions play with that content. One mantra to keep in mind is “Think Like the Testmaker”, reminding yourself to pay just as much attention to why the wrong answer you chose was tempting (how did the author trick you) as to why the correct answer was right.
Arguably the single most common trap the authors set for you is evident in this question, which we invite you to answer before you read the rest of this post:
Uncle Bruce is baking chocolate chip cookies. He has 36 ounces of dough (with no chocolate) and 15 ounces of chocolate. How much chocolate is left over if he uses all the dough but only wants the cookies to consist of 20% chocolate?
Now, we don’t want to gloss over the math here but there’s plenty of opportunity to practice with word problems and ratios in other posts and resources, so let’s cut to the true takeaway here. Most students will correctly arrive at the amount of chocolate used by employing a method similar to:
If the 36 ounces of dough are to be 80% of the total weight, then 36 = 4/5 * total.
That means that the total weight is 45 ounces, and so when we subtract out the 36 ounces of dough, there’s 9 ounces of chocolate in the cookies.
So…the answer is E. Right?
Wrong. Go back and double-check the question – the question asks for how much chocolate is LEFT OVER, not how much is USED. To be correct, you’d need to go back to the 15 original ounces of chocolate, subtract the 9 used, and correctly answer that 6 were left.
What’s the trap? GMAT questions are frequently set up so that you can answer the wrong question. If a question asks you to solve for y, it typically makes it easier to first solve for x…and then x is a trap answer. If a question asks you to strengthen a conclusion, the best way to weaken it is likely to be an answer choice. If a question asks for the maximum value, the minimum is going to be a trap.
The most common wrong answer to any problem on the GMAT is the right answer to the wrong question.
So take precaution – to avoid this trap, make sure that you:
- Circle the variable for which you’re solving, or write down the question at the top of your work.
- Jot a question mark at the top of your noteboard on test day, and tap it with your pen before you submit your answer to double check “did I answer the right question?”
- Keep track of your units in word problems (minutes vs. seconds, amount used vs. amount remaining) and double check the units of your answer against the question
- Make note of every time you make that mistake in practice, and as a more general tip be sure not to write off silly mistakes as just “silly mistakes”. If you made them in practice, you’re susceptible to them on the test, so make a note to watch out for them particularly if you’ve made the same mistake twice.
Few outcomes are more disappointing than doing all the work correctly but still getting the question wrong. The GMAT doesn’t do partial credit, so on a question like this falling for the trap is just as bad as not knowing how to get started. Get credit for what you know how to do – make sure you pause before you submit your answer to make sure that it answers the proper question!
By Brian Galvin