Question

In a class of 100 students there are 70 boys whose average marks in a subject are 75. If the average marks of the complete class are 72, then what are the average marks of the girls

• A. 73
• B. 65
• C. 68
• D. 74

Answer 1

The correct option is B 65

Let the average marks of the girls students be x,
then $72=\frac{70\times 75+30\times x}{100}$ (Number of girls $=100-70=30)$
i.e., $\frac{7200-5250}{30}=x;\therefore x=65.$