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?

A. 65000

B. 75000

C. 85000

D. 95000

E. 105000

1. 2020 AMC 8 官方解析

The total population of all the cities equals the number of cities multiplied by the average city population. There are 20 cities, and the dashed line shows that the average population is between 4500 and 5000. It follows that the total population of the 20 cities is between $20 \cdot 4500 = 90,000$ and $20 \cdot 5000 = 100,000$. Only choice (D) 95,000 is within 5000 of the actual total population.

所有城市的总人口等于城市数乘以城市平均人口数．有20个城市，虚线显示平均人口数量在 $4500$ 和 $5000$ 之间．因此，20个城市的总人口数量在 $20 \cdot 500 = 90,000$ 和 $20 \cdot 5000 = 100,000$ 之间．只有选择(D)95,000才能使得实际总人口在 $5000$ 以内．