in an examination 3/5th of the students that appeared failed by 10 mark sand 1/5th of the students got 10 marks above the pass mark.each of the remaining students got 20 marks above the pass mark.their average mark is 62 marks.the pass mark is?pl.provide sol.

1) 64
2) 66
3) 62
4) 56

• 3/5th of the students that appeared failed by 10 marks
  Hence 3x/5 students get marks = y−10
  1/5th of the students got 10 marks above the pass marks
  Hence x/5 students get marks = y+10
  Remaining students = x−(3x/5 +x/5) =x/5
  Marks of each of the remaining students got 20 marks above the pass mark.
  Hence x/5 students get marks = y+20
  Average marks of the students={(3x/5)×(y−10)+(x/5)×(y+10)+ x/5)×(y+20)}/x
  ={(3/5)×(y−10)+(1/5)×(y+10)+ 1/5)×(y+20)}
  The average marks of the students = 62
  Hence {(3/5)×(y−10)+(1/5)×(y+10)+ (1/5)×(y+20)}=62
  →(3y−30)+(y+10)+y(+20)}=310
  or 5y = 310
  or y = 62
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