In a class there are 80 students and their average marks in the annual examination is 45.If the average marks of passed students is 55 and the average marks of failed students is 30,then find out the number of students who failed.

(a)48
(b)32
(c)36
(d)None of these

• b)32
  
  Let the number of students failed = x
  Number of students passed = 80-x
  
  Average marks of students = 45
  Total marks of students = 45*80 = 3600
  
  Average marks of failed students = 30
  Total marks of failed students = 30*x
  
  Average marks of passed students = 55
  Total marks of passed students = 55*(80-x)
  
  30x + 55*(80-x) = 3600
  25x = 800
  x = 32
  
• 10 years agoHelpfull: Yes(1) No(0)
• 45*80=55p+30(80-p)
  therfore p=48
  
  failed =32
• 10 years agoHelpfull: Yes(1) No(0)