Question

The average marks of class 100 students is 75. If the average marks of the students who passed the examination is 80 and the average marks of the studentswho failed in tha examination is 30. Find the number of student who passed the examination.

Answer 1

Let the number of students who passed the examination be x. Therefore the number of students who failed the examination will be (100 -x).

According to question the average marks of passed student =80

The total marks scored by the passed students= 80x (80 * x)

Similarly the total marks scored by failed students= 30(100-x)

Now the total scored by all the students= 7500

Now,

80x + 3000 -30x= 7500
50x = 7500-3000
50x = 4500
x= 90

Number of failed student= 10
Number of passed student=90

Note: The formula used is
(Marks scored/Number of students) = Average marks

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