Question

在 East Westmore 县，统计学家估计每 $8$ 小时出生一个婴儿，每天死亡一人。四舍五入到最接近的百位，East Westmore 每年人口增加多少人？

In the county of East Westmore, statisticians estimate there is a baby born every $8$ hours and a death every day. To the nearest hundred, how many people are added to the population of East Westmore each year?

$600$

$700$

$800$

$900$

$1000$

答案：B

知识点：速率估算

难度评级：660

视频讲解：

Click to load, then click again to play

文字解答：

每 $8$ 小时出生 $1$ 个婴儿，所以每 $24$ 小时出生 $3$ 个婴儿。因此每天有 $3$ 人出生、 $1$ 人死亡，平均每天人口净增加 $2$ 人。一年有 $365$ 天，每天净增加 $2$ 人，所以一年净增加约 $2\cdot 365 = 730$ 人，约为 $700$ 。

所以正确答案是 B。

Since we have $1$ birth every $8$ hours, we have $3$ births every $24$ hours. Therefore, we have $3$ births a day and $1$ death a day. The net change in population every day should be on average $2.$ Since we have $365$ days in a year and $2$ added to the population every day, the net change in population should be around $2\cdot 365 = 730 .$ This is approximately $700.$

Thus, the answer is B .

2012 AMC 8 第 2 题

答案：B

难度评级：660

视频讲解：

文字解答：

其他年份的第 2 题