2007 AMC 8 Problem 6

Below is the professionally curated solution for Problem 6 of the 2007 AMC 8, from LIVE by Po-Shen Loh. You can also try the full timed exam, view all 2007 AMC 8 solutions, or check the answer key.

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Concepts:percentage estimation

Difficulty rating: 940

The average cost of a long-distance call in the USA in $1985$ was $41$ cents per minute, and the average cost of a long-distance call in the USA in $2005$ was $7$ cents per minute. Find the approximate percent decrease in the cost per minute of a long-distance call.

$7$

$17$

$34$

$41$

$80$

Solution:

The decrease in cost is $41-7=34$ cents per minute.

The percent decrease is $100\cdot\dfrac{34}{41}\%$ , which is a little more than $80\%$ , so the closest answer is $80$ .

Thus, E is the correct answer.

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