Question

Gotham City 的出租车在前 $\dfrac{1}{2}$ 英里收费 $\$2.40$ ，之后每额外 $0.1$ 英里收费 $\$0.20$ 。你计划给司机 $\$2$ 小费。用 $\$10$ 最多可以乘坐多少英里？

The taxi fare in Gotham City is $\$2.40$ for the first $\dfrac{1}{2}$ mile and additional mileage charged at the rate $\$0.20$ for each additional $0.1$ mile. You plan to give the driver a $\$2$ tip. How many miles can you ride for $\$10$ ?

$3.0$

$3.25$

$3.3$

$3.5$

$3.75$

答案：C

知识点：速率钱币

难度评级：1100

解答：

小费固定为 $\$2$ ，从总额中减去后剩 $\$8$ 。这大于 $\$2.40$ ，所以再减去前半英里的车费，并把 $\dfrac{1}{2}$ 英里计入总距离。

现在还有 $\$5.60$ 可用于额外里程。每 $0.1$ 英里收费 $\$0.20$ ，等价于每 $1$ 英里收费 $\$2$ 。因此这笔钱还能乘坐 $5.60 / 2 = 2.8$ 英里。总距离为 $2.8 + \dfrac{1}{2} = 3.3$ 英里。

所以正确答案是 C。

There is a guaranteed $\$2$ tip, so we can subtract that from the total, leaving $\$8.$ This is greater than $\$2.40,$ so we can subtract that and add $\dfrac{1}{2}$ miles to the total distance.

We now have $\$5.60$ to use for additional miles. $\$0.20$ per $0.1$ mile is the same as $\$2$ for $1$ mile. That means one can ride for $5.60 / 2 = 2.8$ more miles with this much money. This leaves a total of $2.8 + \dfrac{1}{2} = 3.3$ miles.

Thus, C is the correct answer.

2011 AMC 8 第 10 题

答案：C

难度评级：1100

解答：

其他年份的第 10 题