WAEC Mathematics 2020 Paper

Concept:The volume of a right pyramid is found by multiplying one-third of the area of its base by its perpendicular height.Explanation:The base is a rectangle with length $9 \text{ cm}$ and width $5 \text{ cm}$.Calculate the base area: $A = 9 \times 5 = 45 \text{ cm}^2$.Let the height of the pyramid be $h \text{ cm}$.The formula for the volume of the pyramid is $V = \frac{1}{3} A h$.Substitute the given volume and base area: $105 = \frac{1}{3} \times 45 \times h$.This simplifies to $105 = 15h$.Solve for $h$ by dividing both sides by 15: $h = \frac{105}{15}$.Therefore, $h = 7$.So the perpendicular height of the pyramid is $7 \text{ cm}$.Answer:$7 \text{ cm}$