AMC 8 1985 Problem 16
AMC8 1985 年第 16 题
比与比例★★★☆☆
The ratio of boys to girls in Mr. Brown's math class is 2:3. If there are 30 students in the class, how many more girls than boys are in the class?
Mr. Brown 的数学班上男生与女生的比例是 2:3。如果班上有 30 名学生，女生比男生多多少人？
- A.1
- B.3
- C.5
- D.6
- E.10
正确答案 · Correct Answer
D
解析 · Solution
Solution 1
Let be half the number of boys. Then there are boys and girls. So 2x+3x=5x=30 and thus x = 6. Therefore, between the number of girls and the number of boys is 3x-2x=x=6.
Since the ratio of boys to girls is , of the students are boys and are girls. Thus the difference between the number of boys and the number of girls is of the number of students in the class, that is .
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