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.

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.