【备考每日练】GMAT数学真题精选实例讲解（二十四练）

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GMAT备考，除了背背背，更重要的就是练练练!通过练习，巩固知识，熟练技巧，最终才能在GMAT考试中发挥出色，取得好成绩，所以练习的重要性不言而喻。因此，小编为大家精心准备了GMAT考试各类题型的练习题和答案解析，帮助大家每日一练，为考试做好准备。一起来看今天的题目吧。

今日练习题为数学题，题目如下

Of all the students in a certain dormitory, 1/2 are first-year students and

the rest are second-year students. If 4/5 of the first-year students have not

declared a major and if the fraction of second-year students who have declared a

major is 3 times the fraction of first-year students who have declared a major,

what fraction of all the students in the dormitory are second-year students who

have not declared a major?

A 1/15

B 1/5

C 4/15

D 1/3

E 2/5

正确答案：

B

解题思路：

设总人数为100，那么，一年级学生有50个，二年级50个。一年级中没定专业的有40个，定了的有10个。由于二年级学生中定了专业的比例是一年级的3倍，所以二年级学生定了专业的有30个，没定专业的有20个。所以，二年级学生中，没定专业的人数与总人数的比例是20%，即1/5