The average score of boys in an examination of a school is 71 and that of girls is 73.The average score of the school in that examination is 71.8.Find the ratio of the number of boys to the number of girls that appeared in the examination.

• 3:2 is the ratio.
  
  Let Number of boys = A
  And Number of girls =B
  
  And Average score of boys = X1
  And Average score of girl = X2
  The Average score = X
  
  Therefore,
  X1 = 71 ; X2 = 73 ; X = 71.8 ;
  
  So,
  --> X = [(A*X1)+(B*X2)]/(A+B)
  --> 71.8 = [(A*71)+(B*73)]/(A+B)
  --> 71.8(A+B) = (A*71)+(B*73)
  --> 71.8A + 71.8B = 71A + 73B
  --> 71.8A - 71A = 73B - 71.8B
  --> 0.8A = 1.2B
  So,
  A/B = 1.2(10) / 0.8(10)
  A/B = 12/8
  
  Therefore,
  A:B = 12:8
  A:B = 3:2
  
  The ratio of the number of boys to the number of girls that appeared in the examination is 3:2.
• 12 years agoHelpfull: Yes(3) No(0)
• 1.45...(x/n)=71
  .........(y/m)=73
  .....(x+y)/(m+n)=71.8
  ......solve it for (x/y)=p
  
• 12 years agoHelpfull: Yes(1) No(2)