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The average of marks of 28 students in Mathematics was 50; 8 students left the school, then this average increased by 5. What is the average of marks obtained by the students who left the school ?
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- 50.5
- 37.5
- 42.5
- 45
- 50.5
Correct Option: B
The average of marks of 28 students in Mathematics = 50
Total marks of 28 students = 28 × 50 = 1400
When 8 students left , The average of marks of 20 students = 55
Total marks of 20 students = 20 × 55 = 1100
∴ Total marks of 8 students = 1400 – 1100 = 300
∴ Average = 300 ÷ 8 = 37.5
