2009 AMC 8 Problem 8
Attempt Problem 8 of the 2009 AMC 8 below, then check your answer against the professionally curated solution from LIVE by Po-Shen Loh. You can also try the full timed exam, view all 2009 AMC 8 solutions, or check the answer key.
All problems are used with official legal permission of the Mathematical Association of America (MAA).
8.
The length of a rectangle is increased by and the width is decreased by What percent of the old area is the new area?
Answer: B
Small hint:
Multiply the scale factors for length and width.
Big hint:
The new area is times the old area.
Solution:
Let the old length and width be and so the old area is
The new length is and the new width is Thus the new area is
This shows that the new area is of the old area.
Thus, B is the correct answer.
Problem 8 in other years
- 1985 AMC 8
- 1986 AMC 8
- 1987 AMC 8
- 1988 AMC 8
- 1989 AMC 8
- 1990 AMC 8
- 1991 AMC 8
- 1992 AMC 8
- 1993 AMC 8
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