As you learned already, Plugging In is a powerful technique for solving SAT algebra problems. It is also
very useful on geometry problems. On some problems, you will be able to plug in ballpark values for
missing information and then use the results either to find the answer directly or to eliminate answers that
could not possibly be correct.
Here’s an example:
20.The base of triangle T is 40 percent less than the length of rectangle R. The height of
triangle T is 50 percent greater than the width of rectangle R. The area of triangle T is
what percent of the area of rectangle R ?
A) 10
B) 45
C) 90
D) 110Here’s How to Crack It
This is a really hard problem. Don’t worry—you’ll still be able to find the right answer by sketching and
plugging in.
When plugging in, always use numbers that are easy to work with. Let’s say the length of the rectangle is
10; that means that the base of the triangle, which is 40 percent smaller, is 6. Now if we plug 4 in for the
width of rectangle R, then the height of triangle T is 6. You should come up with two sketches that look
like this:
T has an area of bh, or 18. R has an area of 40. Now set up the translation: 18 = (40), where x
represents what percent the triangle is of the rectangle.
Solve for x and you get 45. The correct answer is (B).