Every student in a room is either a junior or a senior. There is at least one junior and at least one senior in the room. If 1/2 of the juniors is equal to 2/3 of the seniors, what fraction of the students in the room are juniors?
Choose the correct option
A) 4 / 7 B) 1 / 3 C) 5 / 3 D) 12 / 7 E) 17 / 20

Rationale: let total number of juniors = j total number of seniors = s ( 1 / 2 ) j = ( 2 / 3 ) s = > s = 3 / 4 j total number of students = j + s = ( 7 / 4 ) j fraction of the students in the room are juniors = j / ( j + s ) = j / [ ( 7 / 4 ) j ] = 4 / 7 answer a
Answer: A