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The average of marks obtained by 120 candidates in a certain examination is 35. If the average marks obtained by passed candidates are 39 and those of the failed candidates are 15, what is the number of candidates who passed the examination ?
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- 100
- 120
- 150
- 140
- 100
Correct Option: A
The average of marks obtained by 120 candidates = 35.
Let the number of successful students = y
∴ Number of unsuccessful students = 120 – y
According to the question,
⇒ y × 39 + (120 – y) × 15 = 120 × 35
⇒ 39y – 15y + 1800 = 4200
⇒ 24y = 4200 – 1800 = 2400
⇒ y = 100
