Estimating is a lost art on the SAT. You can put yourself in an excellent guessing position by estimating the answer on easy and medium questions. I often use this strategy with the plug-the-answers-in strategy. I can quickly eliminate several wrong answers and then only need to check one or two answers to see which is correct.
The science of learning is demonstrating that the ability to make accurate estimates is closely tied to the ability to understand and solve problems.
Estimation, this research shows, is not an act of wild speculation but a highly sophisticated and valuable skill that, some experts say, is often given short shrift in the curriculum.
So increasing your skill at estimating can pay off. Let’s see what this looks like in an actual SAT problem. This is question 5 from Test 5, Section 2 on page 639 in the Blue Book.
Let’s make a table to clearly see what values we are working with.
Now, let’s estimate. What if I doubled the force? What would that do to the length?
So doubling the force to 30 lbs would stretch the spring to 16 cm. But we need to go even further – to 20 cm. So we clearly need more force.
Looking at our answer choices, we can cross out 23, 27 and 30.5.
Here’s a video on how to solve out the whole problem.
Let’s look at one more example. This is question 7 from Test 6, Section 4 on page 714 from the Blue Book.
Hmm. I know the formula for area of a triangle is 1/2 b*h. And it looks like the base is 6/7 h. Which is practically h. So the area is going to be a little bit less than 1/2 h*h or 1/2 h². Looking at the answer choices, C is the only one that is close to 1/2 – 3/7 is just under 1/2 (which would be 3.5/7)
Try estimating the answer for this medium question (Test 6, Section 8, Question 12 in the Blue Book. How many wrong answers can you eliminate right off the bat?