AMC8 2023

AMC8 2023 · Q3

AMC8 2023 · Q3. It mainly tests Fractions.

Wind chill is a measure of how cold people feel when exposed to wind outside. A good estimate for wind chill can be found using this calculation \[(\text{wind chill}) = (\text{air temperature}) - 0.7 \times (\text{wind speed}),\] where temperature is measured in degrees Fahrenheit $(^{\circ}\text{F})$ and the wind speed is measured in miles per hour (mph). Suppose the air temperature is $36^{\circ}\text{F}$ and the wind speed is $18$ mph. Which of the following is closest to the approximate wind chill?

风寒是衡量人们在室外暴露于风中时感觉多冷的一种度量。风寒的一个良好估计可以使用以下计算公式得到 \[(\text{风寒}) = (\text{空气温度}) - 0.7 \times (\text{风速}),\] 其中温度以华氏度 $(^{\circ}\text{F})$ 测量，风速以英里每小时 (mph) 测量。假设空气温度为 $36^{\circ}\text{F}$，风速为 $18$ mph。下列哪个是最接近于近似风寒的数值？

(A) \ 18 \ 18

(B) \ 23 \ 23

(D) \ 32 \ 32

(E) \ 35 \ 35

Answer

Correct choice: (B)

正确答案：（B）

Solution

By substitution, we have \begin{align*} (\text{wind chill}) &= 36 - 0.7 \times 18 \\ &= 36 - 12.6 \\ &= 23.4 \\ &\approx \boxed{\textbf{(B)}\ 23}. \end{align*}

通过代入，我们有 \begin{align*} (\text{风寒}) &= 36 - 0.7 \times 18 \\ &= 36 - 12.6 \\ &= 23.4 \\ &\approx \boxed{\textbf{(B)}\ 23}. \end{align*}

Topics

AR.001 Fractions