The average age of all boys in the class is 16.66, while the average age of all girls in the same class is 18.75. Thus the average marks of all 40 students in the class is 17.5 what is the number of girls in the class?
(A) 12
(B) 16
(C) 18
(D) 20
(E) Data Insufficient

• x=girls, 40-x=boys. (since 40 students are there).
  16.66(40-x)+18.75x=17.5*40.
  on solving we get x=16.
  so (c)16 is the correct answer.
• 14 years agoHelpfull: Yes(13) No(5)
• ans:E
• 14 years agoHelpfull: Yes(6) No(8)
• x=girls, 40-x=boys (since 40 students are there)
  16.66(40-x)+18.75(x)=40*17.5
  on solving x=16
  therefore c)16 is the correct option
• 14 years agoHelpfull: Yes(6) No(2)
• Ans:c(18)
• 14 years agoHelpfull: Yes(3) No(4)
• (E) Data Insufficient
• 14 years agoHelpfull: Yes(2) No(7)
• Option B i.e 16
• 10 years agoHelpfull: Yes(1) No(0)
• the question be: either on age or on marks completely...... or else there is no meaning to it ( no relation between marks & age )in that case @sonesh is correct
  
• 10 years agoHelpfull: Yes(1) No(0)
• @Sonesh
  there is no relevance between marks and ages ..how you write that equation?
• 10 years agoHelpfull: Yes(0) No(0)
• data insufficient
  
• 9 years agoHelpfull: Yes(0) No(0)