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The average markes obtained by 120 students in an examination is 30. if the aveage marks of passed students is 40 and that of the failed students is 10. what is the 25% of the number of students who passed the examination ?
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- 30
- 20
- 40
- 15
Correct Option: B
Let number of passed students = N
Total marks = 120 x 30
According to the question,
40N + (120 - N) x 10 = 120 x 30
⇒ 3600 = 40N + 1200 - 10N
⇒ 30N = 2400
∴ N = 2400/30 = 80
∴ 25% of 80 = 80/4 = 20
