Question 1: In a class, the average height of boys is
165 cm, and the average height of girls is 155 cm. If
the average height of the whole class is 160 cm, what
is the ratio of boys to girls in the class?



Answer :

To determine the ratio of boys to girls in the class, we can use the information given about the average heights of boys, girls, and the class as a whole. Let's denote \( x \) as the number of boys and \( y \) as the number of girls in the class. We want to find the ratio \( \frac{x}{y} \). We are given the following average heights: - Average height of boys, \( \text{boy\_avg\_height} = 165 \) cm, - Average height of girls, \( \text{girl\_avg\_height} = 155 \) cm, - Average height of the whole class, \( \text{class\_avg\_height} = 160 \) cm. Using the formula for average height of the class, we can express the total height of all boys combined and all girls combined as: \[ \text{boy\_avg\_height} \times x + \text{girl\_avg\_height} \times y = \text{class\_avg\_height} \times (x + y) \] Substituting the values, we get: \[ 165x + 155y = 160(x + y) \] Now, expand the right side: \[ 165x + 155y = 160x + 160y \] Rearrange the equation to bring like terms together and solve for \( x \) in terms of \( y \): \[ 165x - 160x = 160y - 155y \] \[ 5x = 5y \] Divide both sides by 5: \[ x = y \] Therefore, the ratio of the number of boys to girls \( \left( \frac{x}{y} \right) \) in the class is 1:1. This means there is an equal number of boys and girls in the class.