2013 AMC 10A 第 10 题

Question

一束花包含粉玫瑰、红玫瑰、粉康乃馨和红康乃馨。粉色花中有三分之一是玫瑰，红色花中有四分之三是康乃馨，全部花中十分之六是粉色的。康乃馨占全部花的百分之几？

A flower bouquet contains pink roses, red roses, pink carnations, and red carnations. One third of the pink flowers are roses, three fourths of the red flowers are carnations, and six tenths of the flowers are pink. What percent of the flowers are carnations?

15

30

40

60

70

答案：E

知识点：分数百分数

难度评级：1280

小提示：

分别计算粉康乃馨和红康乃馨。

Break the bouquet into pink carnations and red carnations

大提示：

对粉花和红花分别使用给出的比例。

Use the given fractions of pink and red flowers separately

解答：

设总花数为

x

。粉色花有

0.6x

朵，红色花有

0.4x

朵。

于是粉玫瑰有

\dfrac{1}{3} \cdot 0.6x = 0.2x

朵，所以粉康乃馨有

0.4x

朵。

另外红康乃馨有

\dfrac{3}{4} \cdot 0.4x = 0.3x

朵。因此康乃馨共有

0.3x + 0.4x = 0.7x

朵，占全部花的

70\%

。

所以正确答案是 E。

Let the total number of flowers be

x.

There are

0.6x

pink flowers and

0.4x

red flowers.

Then there are

\dfrac{1}{3} \cdot 0.6x = 0.2x

pink roses, which means there are

0.4x

pink carnations.

There are also

\dfrac{3}{4} \cdot 0.4x = 0.3x

red carnations. This means there are

0.3x + 0.4x = 0.7x

carnations. This is

70\%

of the total flowers.

Thus, E is the correct answer.

2013 AMC 10A 第 10 题

答案：E

难度评级：1280

小提示：

大提示：

解答：

其他年份的第 10 题