Description:
Working Backwards questions allow you to test the answers by plugging them
back into the questions. Work backwards when questions ask you to find a number
that will make the question true.
Approach:
First, plug answer/choice C back into the question. Then, based on how close C
fulfills the question's constraints, try the other choices until one works.
1) Steps to Working Backwards
-
Test out answer choice C first. This is a good move because the answers
on math questions are always in order in terms of size.
-
If answer C is too big, eliminate D and E and move to choice B. If C is
too small, move to answer D.
-
Whichever answer satisfies the problem's criteria is the right choice.
2) Practice:
If the sum of three consecutive multiples of 3 is 45, what is the smallest of
the three numbers?
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9
-
12
-
15
-
18
-
21
If 34x + 4
= 272x, what is the value of x?
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0
-
1
-
2
-
3
-
4
