Question

一个手机套餐每月费用为 $\$20$ ，外加每条短信 $5$ ¢，以及超过 $30$ 小时后每分钟 $10$ 美分。Michelle 一月份发送了 $100$ 条短信，并通话 $30.5$ 小时。她需要支付多少钱？

A cell phone plan costs $\$20$ each month, plus $5$ ¢ per text message sent, plus $10$ ¢ for each minute used over $30$ hours. In January Michelle sent $100$ text messages and talked for $30.5$ hours. How much did she have to pay?

$\$24.00$

$\$24.50$

$\$25.50$

$\$28.00$

$\$30.00$

答案：D

知识点：钱币单位换算

难度评级：720

解答：

月费为 $\$20$ 。短信费用为此外，她的通话时间超过套餐的 $30$ 小时 $.5$ 小时，也就是 $30$ 分钟。 $100 \cdot 5 \text{ cents} = 500 \text{ cents} = \$5$

因此超时通话费用为 $30 \cdot 10 \text{ cents} = 300 \text{ cents} = \$3.$

总费用为 $\$20 + \$5 + \$3 = \$28.$

所以正确答案是 D。

Michelle has to pay $\$20$ for the monthly fee. She also has to pay $100 \cdot 5 \text{ cents} = 500 \text{ cents} = \$5$ for the text messages. Finally she talked for $.5$ hours, $30$ minutes, over $30$ hours.

This means she has to pay an extra $30 \cdot 10 \text{ cents} = 300 \text{ cents} = \$3.$

Her total cost is $\$20 + \$5 + \$3 = \$28.$

Thus, D is the correct answer.

2011 AMC 10A 第 1 题

答案：D

难度评级：720

解答：

其他年份的第 1 题