A hollow metal pipe is long and has an external radius of
MATHEMATICS · Subjective · GCSE · Mathematics · Geometry and Measures · Geometry and Measures
Problem
A hollow metal pipe is 2m long and has an external radius of 7cm. Only the outside curved surface of the pipe has to be painted. A student decides to use the total surface area of a closed cylinder to estimate the amount of paint required.
(i) State, giving one reason, whether the student’s choice of surface area is correct.
(ii) Calculate the correct area that should actually be painted.
(iii) If paint costs ₹45 per square metre, how much money would be wasted by following the student’s original estimate?