WAEC Mathematics 2019 Objective — Question 22

Question 22 of 145 from the West African Examinations Council (WAEC) Mathematics 2019 Objective paper, with the correct answer and a full explanation.

22. The total surface area of a solid cylinder is 165cm². If the base diameter is 7cm, calculate its height. [Take π = 22/7]

A. 7.5cm
B. 4.5cm
C. 4.0cmCorrect
D. 2.0cm

Explanation

T.S.A. = C.S.A + 2πr² = 2πr(h+r), r=3.5cm. 165 = 2×(22/7)×3.5×(h+3.5) = 22(h+3.5) ⇒ 7.5 = h+3.5 ⇒ h = 4.0cm.

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