Question

Chandra 向一家网络服务提供商支付固定月费，另按连接时长支付费用。她十二月的账单是 $12.48；一月因为连接时间是十二月的两倍，账单为 $17.54。固定月费是多少？

Chandra pays an on-line service provider a fixed monthly fee plus an hourly charge for connect time. Her December bill was $12.48, but in January her bill was $17.54 because she used twice as much connect time as in December. What is the fixed monthly fee?

$2.53

$5.06

$6.24

$7.42

$8.77

答案：D

知识点：方程组一次方程

难度评级：1030

解答：

一月只有连接时间翻倍，所以账单增加的 $\$17.54 - \$12.48 = \$5.06$ 就是十二月的连接时长费用。

因此固定月费是 $\$12.48 - \$5.06 = \$7.42$ 。

所以正确答案是 D。

January doubled only the connect time, so the increase $\$17.54 - \$12.48 = \$5.06$ equals December's connect-time cost.

The fixed monthly fee is therefore $\$12.48 - \$5.06 = \$7.42.$

Thus, the correct answer is D.

2000 AMC 10 第 4 题

答案：D

难度评级：1030

解答：

其他年份的第 4 题