Question

From a school, 90 boys and 30 girls appeared for a public examination. The average marks of boys is found to be 45 whereas the average marks of girls is 70. What is the school average?

• A. 61.50
• B. 51.25
• C. 40.50
• D. 51.52

Answer 1

The correct option is B 51.25

Number of boys = 90
Average marks of boys =45
Total marks of 90 boys $=90\times 45=4050$
Number of girls = 30
Average marks of girls =70
$\therefore$ Total marks of 30 girls $=30\times 70=2100$
Total marks secured by 90 boys and 30 girls
= 4050 + 2100 = 6150
Number of boys and girls
= 90 + 30 = 120
$\therefore$ Average marks of the school
$=\frac{6150}{120}=51.25$