Question

students were surveyed about their favorite colors 1\4 of the student preferred red, 1/8 student of the students preferred blue and 3/5 of the remaining students preferred green. If 15 students preferred green how many students were surveyed?

Answer 1

All we have to find the fraction of students who preferred green and go from there.
Subtracting blue and red out of the all students,
1- (1/8+1/4)
1- 3/8
5/8 is the remaining students, in order to find 3/5 of the remaining students, we multiply by 3/5

5/8(2/5) = 3/8
3/8 preferred green, which was 15 students. In order to get 100% of the whole population (1), we multiply by 8/3:

15(8/3) = 40

40 students were surveyed in total.