A metal pipe is 77 cm long. The inner diameter of its cross-section is 4 cm and the outer diameter is 4.4 cm. What is its inner curved surface area?

Updated on May 31, 2025 | By Learnzy Admin

Length of the pipe = 77 cm
Inner diameter = 4 cm 
Then Inner radius of pipe is = 4 ÷ 2 = 2 cm

Formula for curved surface area (CSA) of a cylinder:

CSA = 2 × π × r × h
Where:
r = radius = 2 cm
h = height (length of pipe) = 77 cm
π = 22/7

Substitute values then CSA is

CSA = 2 × (22/7) × 2 × 77
CSA = (4 × 22 × 77) / 7
CSA = (6776) / 7 = 968 cm²

Hence inner curved surface area is 968 cm²

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