2021 · Q77
Let the average score of a class of boys and girls in an examination be p. The ratio of boys and girls in the class is 3 ∶ 1. If the average score of the boys is (p + 1), then what is the average score of the girls?
Elementary MathematicsRatio and Proportion
- A(p − 1)
- B(p − 2)
- C(p − 3)
- Dp
Explanation
With boys : girls = 3 : 1, the overall mean is (3(p+1) + g)/4 = p, where g is the girls' average. So 3p + 3 + g = 4p, giving g = p − 3. Hence option C.