The number of students in the four classes of the sixth grade of Hongxing Primary School is between 165 and 170, and the ratio of male to female is 3:4. What is the total number of sixth grade students?
红星小学六年级四个班的学生人数在165到170之间，其中男女人数的比是3：4，那么六年级学生的总人数是多少
<result>168</result>