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1. Average mark in Math in a class of 40 students is 45. Average mark of all the 30 boys is 50. Then the average mark obtained by the girls is :
- A. 30
- B. 30
- C. 30
- D. 30
Answer: Option A
Explanation:
No. of students = 40
No. of Boys = 30
No. of Girls = 10
Average of 40 stuents = 45
Total of students = 45 *40 = 1800
Aerage of 30 students = 50
Total of 30 = 30 * 50 = 1500
Total of 10 girls = 1800 - 1500 = 300
Average mark of 10 girls = 300/10 = 30
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