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The average marks of 50 students in a class is 72. The average marks of boys and girls in that subject are 70 and 75 respectively. The number of boys in the class is
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- 20
- 35
- 25
- 30
- 20
Correct Option: D
Let Number of students in the class = n
∴ Number of girls = 50 – n
According to the question,
n × 70 + (50 – n) × 75 = 50 × 72
⇒ 70n + 3750 – 75n = 3600
⇒ 3750 – 5n = 3600
⇒ 5n = 3750 – 3600 = 150
| ⇒ n = | = 30 | |
| 5 |
