1988 AMC 8 第 12 题

Question

假设把送一个人去火星的估计费用

20

十亿美元，平均分摊给美国

250

百万人。那么每个人应分摊

Suppose the estimated

20

billion dollar cost to send a person to the planet Mars is shared equally by the

250

million people in the U.S. Then each person’s share is

\$40

\$50

\$80

\$100

\$125

知识点：位值

用十的幂写数：

20

十亿美元

= 2 \times 10^{10}

，

250

百万人

= 2.5 \times 10^{8}

Write the numbers with powers of ten:

20

billion

= 2 \times 10^{10}

and

250

million

= 2.5 \times 10^{8}

用总费用除以人数

Divide the total cost by the number of people

每个人分摊的费用是

\dfrac{20 \times 10^9}{250 \times 10^6} = \dfrac{2 \times 10^{10}}{2.5 \times 10^{8}}\text{。}

这等于

0.8 \times 10^{2} = 80

。

所以正确答案是 C。

Each person’s share is

\dfrac{20 \times 10^9}{250 \times 10^6} = \dfrac{2 \times 10^{10}}{2.5 \times 10^{8}}.

This equals

0.8 \times 10^{2} = 80.

Thus, the correct answer is C .

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