The average marks of the students in four sections A, B, C
and D of a schoolis 60%. The average marks of the students of A, B C and D
individually are 45%, 50%, 72% and 80%, respectively. If the average marks of the
students of sections A and B together is 48% and that of the students of B and
C together is 60%, what is the ratio of the number of students in sections A
and D ?(1) 2 : 3(2) 4 : 3(3) 5 : 3(4)
3 : 5

1) 2:3
2) 4:3
3) 5:3
4) 3:5

• (2) 4 : 3
  If A,B,C,D are number of students in section A,B,C,D respectively , then
  45A+50B+72C+80D= 60*(A+B+C+D)
  -15A-10B+12C+20D=0
  
  also 48A+48B= 45A+50B or B=2/3 A
  and 60B+60C= 50B+72C; B=6/5 C; C=5/9 A
  
  solving these equations,
  A/D =4/3
• 12 years agoHelpfull: Yes(0) No(0)