2009 AMC 12B 第 2 题

Question

油漆工 Paula 原本有刚好够刷

30

间同样大小房间的油漆。不幸的是，在去工作的路上，有三罐油漆从卡车上掉了下来，所以她只剩下够刷

25

间房间的油漆。她刷这

25

间房间用了多少罐油漆？

Paula the painter had just enough paint for

30

identically sized rooms. Unfortunately, on the way to work, three cans of paint fell off her truck, so she had only enough paint for

25

rooms. How many cans of paint did she use for the

25

rooms?

10

12

15

18

25

答案：C

知识点：比与比例

难度评级：900

小提示：

丢失的

3

罐油漆对应她少刷的

5

间房间。

The

3

lost cans account for the

5

rooms she can no longer paint

大提示：

油漆罐数与房间数的比是

3 : 5

。

The ratio of cans to rooms is

3 : 5

解答：

丢失

3

罐使她少刷

5

间房间，所以

3

罐油漆能刷

5

间房间，每间房需要

\dfrac{3}{5}

罐。

刷

25

间房间需要

25 \cdot \dfrac{3}{5} = 15

罐。

所以正确答案是 C。

Losing

3

cans cost her

5

rooms, so

3

cans paint

5

rooms and each room needs

\dfrac{3}{5}

of a can.

For

25

rooms she used

25 \cdot \dfrac{3}{5} = 15

cans.

Thus, the correct answer is C.

2009 AMC 12B 第 2 题

答案：C

难度评级：900

小提示：

大提示：

解答：

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