2012 AMC 10B Problem 2

Attempt Problem 2 of the 2012 AMC 10B 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 2012 AMC 10B solutions, or check the answer key.

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2.

A circle of radius 55 is inscribed in a rectangle as shown. The ratio of the length of the rectangle to its width is 2:1.2:1. What is the area of the rectangle?

50 50

100 100

125 125

150 150

200 200

Answer: E
Concepts:circlerectangleratio and proportion
Difficulty rating: 560
Solution:

The smaller side of the rectangle is equal to the diameter, which is 2r=25=10.2r=2\cdot 5=10.

Due to the 2:12:1 ratio, the long side is 102=20.10\cdot 2=20.

Therefore, the area is 2010=200.20\cdot 10=200.

Thus, the correct answer is E .

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