Question

$1985$ 年，美国长途电话平均费用为每分钟 $41$ 美分； $2005$ 年为每分钟 $7$ 美分。求长途电话每分钟费用大约下降了百分之多少。

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.

$7$

$17$

$34$

$41$

$80$

答案：E

知识点：百分数估算

难度评级：940

解答：

费用下降了 $41-7=34$ 美分每分钟。

百分比下降为 $100\cdot\dfrac{34}{41}\%$ ，略大于 $80\%$ ，所以最接近的答案是 $80$ 。

所以正确答案是 E。

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.

2007 AMC 8 第 6 题

答案：E

难度评级：940

解答：

其他年份的第 6 题