2000 AMC 10 第 4 题

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

一月多出来的费用完全来自多用了一份十二月的连接时间。

The extra charge in January comes entirely from one additional December’s worth of connect time

差额

\$17.54 - \$12.48

就是十二月的连接时长费用。

The difference

\$17.54 - \$12.48

equals December’s connect-time cost

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.

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