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

Answer: (B)

65

Answer 2

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., $\frac{7200 - 5250}{30} = x$, ∴ x = 65.