C) 15
D) 20
Here’s How to Crack It
There are a few things going on here. The plane is traveling horizontally, and it is also descending. Start
by figuring out how far it travels horizontally. It moves in that direction at 9 feet per second for 5 seconds,
so it moves horizontally 9 × 5 = 45 feet. It descends 1 foot for every 3 traveled horizontally. If it goes 45
feet horizontally, it will descend more than 3 feet, so eliminate (A). Now see how many “3 feet” are in 45
feet—for each one of them, the plane will descend 1 foot. 45 ÷ 3 = 15, so the plane descends 15 feet, (C).
You may also have noticed that all the numbers in the question are odd. This makes it unlikely that the
answer would be 10 or 20, which are even. If you see things like that, use them as opportunities to
eliminate.
Here’s another example.
6.(5jk^2 + 5j^2 – 2j^2 k) – (jk^2 + 2j^2 k + 5j^2 )Which of the following is equivalent to the expression above?
A) 4 jk^2
B) 4 jk^2 – 4j^2 k
C) 5 j^2 k^4 – 10j^4 k
D) 8 j^2 k^3 + 7j^2 k – 5j^2Here’s How to Crack It
Start with one tiny piece of this ugly looking question. The first set of parentheses starts with a term
containing jk^2 . Check in the second set of parentheses for the same combination of variables and
exponents. The first term there matches, so the first tiny step to take is 5jk^2 – jk^2 = 4jk^2 . There are no other
terms with jk^2 , so the correct answer must contain 4jk^2 . Eliminate (C) and (D). Now you have a fifty-fifty
chance of getting it right, so you could guess and go. Or you could do one more step to determine if the
answer is (A) or (B). The difference between the two answers is the – 4j^2 k term, so focus on the terms in
the expression that contain j^2 k. In the first set of parentheses, you have –2j^2 k, and then you subtract the
2 j^2 k term in the second set of parentheses. –2j^2 k – 2j^2 k = –4j^2 k, so the correct answer is (B).
Write Stuff Down
As you solve questions in small pieces, write down the steps. Don’t keep track of things in your head—
your test booklet is there for your notes. If a figure is given, write the information from the question right
on it.