1/6/2014

Who needs math skills when you can estimate? I'm kidding - but one of the most valuable tools you can use on the SAT and ACT is estimation. Here are a couple of ideas about when to estimate.

1. Before you plunge into the icy waters of a word problem, try taking a logical guess. Just ballpark it. This has a couple of benefits: it gets another part of your brain working, and it gives you something to check your calculation against. Here's an example of a question on which you can estimate first:

Kracked Out energy drink is 5% caffeine, and Whiplash energy drink is 14% caffeine. If I mix 1 ounce of Kracked Out with 3 ounces of Whiplash, what will be the approximate percentage of caffeine in the mixture?

A. 6% B. 9% C. 12% D. 14% E. 19%

I'm not going to explain this one the "math" way, just the estimate way. There is 3 times the amount of the 14% drink than the 5% drink, so the mixture must be a lot closer to 14% than 5%. That gets rid of choices A and B. There's no way the mixture is 14% or more, since we're diluting the 14% drink a little by adding the 5% drink. And that gets rid of choices D and E. So the answer must be C.

2. Another thing to know about the ACT and SAT is that the diagrams are drawn to scale. Even the SAT questions that say "not drawn to scale" are *pretty much* to scale. Any time you see a picture, measure mentally, or better yet, with your answer sheet. Often, you can get the right answer just by measuring accurately.

So remember - estimate first. It will save you from careless errors and make you better at math overall.