AMC8 2020

AMC8 2020 · Q14

AMC8 2020 · Q14. It mainly tests Averages (mean).

There are $20$ cities in the County of Newton. Their populations are shown in the bar chart below. The average population of all the cities is indicated by the horizontal dashed line. Which of the following is closest to the total population of all $20$ cities?

Newton 县有 20 个城市。下图显示了它们的人口。所有城市的平均人口由水平虚线表示。以下哪项最接近所有 20 个城市的总人口？

(A) 65{,}000 65{,}000

(B) 75{,}000 75{,}000

(D) 95{,}000 95{,}000

(E) 105{,}000 105{,}000

Answer

Correct choice: (D)

正确答案：（D）

Solution

We can see that the dotted line is exactly halfway between $4{,}500$ and $5{,}000$, so it is at $4{,}750$. As this is the average population of all $20$ cities, the total population is simply $4{,}750 \cdot 20 = \boxed{\textbf{(D) }95{,}000}$.

我们可以看到虚线正好在 $4{,}500$ 和 $5{,}000$ 之间，所以它在 $4{,}750$。作为所有 20 个城市的平均人口，总人口就是 $4{,}750 \cdot 20 = \boxed{\textbf{(D) }95{,}000}$。

Topics

AR.006 Averages (mean)