Find Out the Number of Students Who Failed? If

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 average marks of failed students is 30, then find out the number of students who failed.

  1. 48
  2. 32
  3. 36
  4. None of these
Desire Adnan Default Asked on 4th August 2015 in Maths.
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  • 1 Answer(s)

    Answer: (2) 32
    Explanation:-
    Let the number of failed students = X
    Then, the number of passed students = 80 – X
    The total number of students in a class = 80

    The average of marks  in the annual examination of 80 students = 45
    Then, the total marks of 80 students = 80 x 45
    = 3600

    The average marks of passed students = 55
    Then, the total marks of passed students = 55 x (80 – X)

    The average marks of failed students = 30
    Then, the total marks of failed students = 30 X

    Then,  55 (80 – X )  + 30 X = 3600
    55 x 80  – 55 X + 30 X = 3600
    4400- 25 X  = 3600
    –  25  X = 3600- 4400
    – 25 X = – 800
    – X =  – 800/25
    – X =  –  32
    X = 32
    Then , the number of failed students is 32
    Hence, the answer is (2) 32.

    Anurag Mishra Professor Answered on 4th August 2015.
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