Question

$2005$ 年，Tycoon Tammy 投资了 $\$100$ ，为期两年。第一年她的投资亏损 $15\%$ ，但第二年剩余投资增长了 $20\%$ 。这两年内 Tammy 的投资变化是多少？

In $2005$ Tycoon Tammy invested $\$100$ for two years. During the first year her investment suffered a $15\%$ loss, but during the second year the remaining investment showed a $20\%$ gain. Over the two-year period, what was the change in Tammy's investment?

$\ 5\%\text{ loss}$

$\ 2\%\text{ loss}$

$\ 1\%\text{ gain}$

$\ 2\% \text{ gain}$

$\ 5\%\text{ gain}$

答案：D

知识点：百分数

难度评级：1040

解答：

$15\%$ 的亏损使投资从 $\$100$ 变为 $0.85\cdot\$100=\$85$ 美元。

$20\%$ 的增长再使其变为 $1.2\cdot\$85=\$102$ 美元。

投资从 $\$100$ 变为 $\$102$ ，也就是增长 $2\%$ 。

所以正确答案是 D。

The $15\%$ loss changes the investment from $\$100$ to $0.85\cdot\$100=\$85$ .

The $20\%$ gain then changes it to $1.2\cdot\$85=\$102$ .

The investment went from $\$100$ to $\$102$ , which is a $2\%$ gain.

Thus, D is the correct answer.

2008 AMC 8 第 9 题

答案：D

难度评级：1040

解答：

其他年份的第 9 题