Question

Malaika 在山上滑雪。下图显示了她沿雪道滑行时，相对于山脚的海拔高度（米）。她总共有多少秒处在 $4$ 米到 $7$ 米之间的海拔高度？

Malaika is skiing on a mountain. The graph below shows her elevation, in meters, above the base of the mountain as she skis along a trail. In total, how many seconds does she spend at an elevation between $4$ and $7$ meters?

$6$

$8$

$10$

$12$

$14$

答案：B

知识点：数据与图表解读

难度评级：1020

视频讲解：

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文字解答：

她第一次达到 $7$ 米是在 $2$ 秒时。

随后她在 $4$ 秒后低于 $4$ 米，这一段贡献 $4 - 2 = 2$ 秒。

接着她在 $6$ 秒时重新高于 $4$ 米，并在 $10$ 秒时再次达到 $7$ 米。

这一段贡献 $10 - 6 = 4$ 秒。最后她在 $12$ 秒时低于 $7$ 米。

再到 $14$ 秒时她低于 $4$ 米，最后一段贡献 $14 - 12 = 2$ 秒。

总时间为秒。所以正确答案是 B。 $2 + 4 + 2 = 8$

The first time that she hits an elevation of $7$ meters is at $2$ seconds.

She then dips below $4$ meters after $4$ seconds. This adds $4 - 2 = 2$ seconds to the total answer.

Malaika then goes above $4$ meters at $6$ seconds. She hits $7$ meters again at $10$ seconds.

This adds $10 - 6 = 4$ more seconds to the total. She finally dips below $7$ meters for the last time at $12$ seconds.

She then falls below $4$ meters at $14$ seconds, finally adding $14 - 12 = 2$ seconds to the total time.

The desired answer is therefore $2 + 4 + 2 = 8$ Thus, B is the correct answer.

2023 AMC 8 第 9 题

答案：B

难度评级：1020

视频讲解：

文字解答：

其他年份的第 9 题