Question
What is the curved surface area of a right circular
cylinder? I. The area of the base of the cylinder is 154 cm². II. The volume of the cylinder is 1540 cm³. Each of the questions below consists of a question and two statements numbered I and II given below it. You have to decide whether the data provided in the statements are sufficient to answer the question. Read both the statements and give answer –Solution
Curved surface area of the cylinder = 2πrh From I. Area of the base is 154 cm² ∴πr² = 154 = 22/7× r² = 154 r² = 7 × 7 r = 7 cm But we can’t find the height of the cylinder. Hence I alone is not sufficient. From II. Volume of the cylinder = πr²h = 1540 So, there are two variables r and h. Hence II alone is not sufficient. From I and II. Volume of the cylinder = πr²h. = 22/7× 7 × 7 × h = 1540 ∴ h = 10 cm ∴ Curved surface area of the cylinder = 2πrh = 2 ×22/7× 7 × 10 = 440 cm² Thus, both the statements together are required to answer the question.
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