2009 AMC 10A 第 18 题

Question

在 Jefferson 夏令营，

60\%

的孩子踢足球，

30\%

的孩子游泳，并且

40\%

的足球队员游泳。四舍五入到最接近的整数百分比，不游泳的孩子中有百分之多少踢足球？

At Jefferson Summer Camp,

60\%

of the children play soccer,

30\%

of the children swim, and

40\%

of the soccer players swim. To the nearest whole percent, what percent of the non-swimmers play soccer?

30\%

40\%

49\%

51\%

70\%

假设有

100

个孩子，并计算踢足球且游泳的人数。

Assume

100

children and count soccer players who swim

求

70

个不游泳者中有多少人踢足球。

Find how many of the

70

non-swimmers play soccer

假设有

100

个孩子：

60

人踢足球，其中

40\%

，也就是

24

人，同时游泳。所以

60 - 24 = 36

名足球队员不游泳。

30

名游泳者和

70

名不游泳者，因此不游泳者中踢足球的比例为

\dfrac{36}{70} \approx 0.514 \approx 51\%\text{。}

所以正确答案是 D。

Take

100

children:

60

play soccer, and

40\%

of them, or

24,

also swim. So

60 - 24 = 36

soccer players do not swim.

There are

30

swimmers and

70

non-swimmers, so the fraction of non-swimmers who play soccer is

\dfrac{36}{70} \approx 0.514 \approx 51\%.

Thus, the correct answer is D.

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