Question

在一堆红、蓝、绿三色弹珠中，红弹珠比蓝弹珠多 $25\%$ ，绿弹珠比红弹珠多 $60\%$ 。设红弹珠有 $r$ 个。这堆弹珠总数是多少？

In a collection of red, blue, and green marbles, there are $25\%$ more red marbles than blue marbles, and there are $60\%$ more green marbles than red marbles. Suppose that there are $r$ red marbles. What is the total number of marbles in the collection?

$2.85r$

$3r$

$3.4r$

$3.85r$

$4.25r$

答案：C

知识点：百分数代数变形

难度评级：1260

解答：

因为 $r = 1.25b$ ，蓝弹珠数为 $b = \dfrac{r}{1.25} = 0.8r$ 。

绿弹珠数为 $g = 1.6r$ 。

总数为 $r + 0.8r + 1.6r = 3.4r$ 。

所以正确答案是 C。

Since $r = 1.25b,$ the number of blue marbles is $b = \dfrac{r}{1.25} = 0.8r.$

The number of green marbles is $g = 1.6r.$

The total is $r + 0.8r + 1.6r = 3.4r.$

Thus, the correct answer is C.

2008 AMC 10A 第 12 题

答案：C

难度评级：1260

解答：

其他年份的第 12 题