AMC8 2023

AMC8 2023 · Q9

AMC8 2023 · Q9. It mainly tests Graphs (coordinate plane), Averages (mean).

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?

Malaika 在山上滑雪。下面图表显示了她滑雪沿小径时相对于山底的海拔高度，单位为米。总共，她在海拔 $4$ 到 $7$ 米之间花费了多少秒？

(A) \ 6 \ 6

(B) \ 8 \ 8

(D) \ 12 \ 12

(E) \ 14 \ 14

Answer

Correct choice: (B)

正确答案：（B）

Solution

We mark the time intervals in which Malaika's elevation is between $4$ and $7$ meters in red, as shown below: The requested time intervals are: - from the $2$nd to the $4$th seconds - from the $6$th to the $10$th seconds - from the $12$th to the $14$th seconds In total, Malaika spends $(4-2) + (10-6) + (14-12) = \boxed{\textbf{(B)}\ 8}$ seconds at such elevation.

我们用红色标记 Malaika 的海拔在 $4$ 到 $7$ 米之间的时间区间，如下所示：请求的时间区间是： - 从第 $2$ 秒到第 $4$ 秒 - 从第 $6$ 秒到第 $10$ 秒 - 从第 $12$ 秒到第 $14$ 秒总共，Malaika 在这样的海拔花费 $(4-2) + (10-6) + (14-12) = \boxed{\textbf{(B)}\ 8}$ 秒。

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