The average marks obtained by 80 students in an examination is 50. If the average marks of passed students is 55 and the number of students who failed the examination are 30, then what is the average marks of students who failed the examination?

41.66

Total marks obtained = 180 x 50 = 9000

Let the number of failed students be x

40x + (180 - x) x 80 = 9000

⇒ x = 135