In a group of fifty students, the average score is 70 . If the average score of 30 boys is 75, then find the average score of the 20 girls.

Correct option is C

Given:
Total students = 50
Total average score = 70
Number of boys = 30
Average score of boys = 75
Number of girls = 20
Formula Used:
Total sum = Average × Number of observations
Solution:
Calculate the total score of all 50 students.
Total score = 50 × 70 = 3500
Calculate the total score of the 30 boys.
Total boys score = 30 × 75 = 2250
Calculate the total score of the 20 girls by subtraction.
Total girls score = 3500 - 2250 = 1250
Calculate the average score of the girls.
Average score of girls = $$\frac{1250}{20}$$​ = 62.5
Final Answer
So the correct answer is (c)