From a school 90 boys and 30 girls appeared for a public examination. The mean mark of boys is found to be 45% whereas the mean mark of girls is 70%. What is the average marks % of the school?
51.25%
Number of boys in the school = 90
Mean marks of boys =45%
Total marks of 90 boys =90×45=4050
Number of girls in the school = 30
Mean marks of girls =70%
∴ Total marks of 30 girls =30×70=2100
Total marks secured by 90 boys and 30 girls
= 4050 + 2100 = 6150
Number of boys and girls who have appeared for exam from the school
= 90 + 30 = 120
∴ Average marks % of school
=6150120=51.25%