WAEC Mathematics 2016 Paper

Concept:The curved surface area of a cylinder is given by the formula $2\pi rh$, where $r$ is the radius of the base and $h$ is the height.Explanation:Given: height $h = 5$ cm and curved surface area $= 110$ cm$^2$.Let the radius of the base be $r$ cm.Using the formula, $110 = 2 \times \frac{22}{7} \times r \times 5$.This simplifies to $110 = \frac{220}{7} r$.Multiply both sides by 7: $770 = 220r$.Divide both sides by 220: $r = \frac{770}{220} = \frac{7}{2} = 3.5$ cm.Answer:The radius of the base is $3.5$ cm, which is option B.