In a class, the average score of 20 boys is 75, and the average score of 30 girls is 80. What is the average score of the entire class?

✓ Correct Answer: Option C

Total score for boys = 20 * 75 = 1500. Total score for girls = 30 * 80 = 2400. Total score for class = 1500 + 2400 = 3900. Total students = 20 + 30 = 50. Average = 3900 / 50 = 78.