Problem:
Suppose a is 150% of b. What percent of a is 3b?
Answer Choices:
A. 50
B. 6632
C. 150
D. 200
E. 450
Solution:
Since a=1.5b, that means b=1.5a. We multiply by 3 to get a 3b term, yielding 3b=2a, and 2a is (D)200% of a.
OR
Without loss of generality, let b=100. Then, we have a=150 and 3b=300. Thus, a3b=150300=2, so 3b is 200% of a. Hence the answer is (D)200%.
The problems on this page are the property of the MAA's American Mathematics Competitions