2005 AMC 12B 第 3 题

Question

Brianna 用周末工作赚来的部分钱购买若干张同价 CD。她用自己钱的五分之一买了全部 CD 的三分之一。买完全部 CD 后，她还剩下自己钱的几分之几？

Brianna is using part of the money she earned on her weekend job to buy several equally-priced CDs. She used one fifth of her money to buy one third of the CDs. What fraction of her money will she have left after she buys all the CDs?

\dfrac{1}{5}

\dfrac{1}{3}

\dfrac{2}{5}

\dfrac{2}{3}

\dfrac{4}{5}

答案：C

知识点：分数比与比例

难度评级：1050

小提示：

买全部 CD 的费用是买其中三分之一的三倍。

Buying all the CDs costs three times as much as buying one third of them

大提示：

全部 CD 花费她钱的

3\cdot\dfrac15

。

All the CDs cost

3\cdot\dfrac15

of her money

解答：

全部 CD 的费用是三分之一 CD 费用的三倍，即她的钱的

3\cdot\dfrac15 = \dfrac35

。

她还剩下自己钱的

1 - \dfrac35 = \dfrac25

。

所以正确答案是 C。

Buying all the CDs costs three times what one third of them cost, namely

3\cdot\dfrac15 = \dfrac35

of her money.

She has

1 - \dfrac35 = \dfrac25

of her money left.

Thus, the correct answer is C.

2005 AMC 12B 第 3 题

答案：C

难度评级：1050

小提示：

大提示：

解答：

其他年份的第 3 题