JAMB Mathematics 2010 Paper

Concept:A cylindrical pipe with one end open has one circular base and a curved surface. Its total surface area is the sum of the curved surface area and the area of that one base.Explanation:Radius of the pipe is $r = 7\, \text{m}$.Length of the pipe is $h = 50\, \text{m}$.Curved surface area of a cylinder is $2\pi rh$.So, curved surface area $= 2\pi(7)(50) = 700\pi\, \text{m}^2$.The open pipe has only one circular end included.Area of one circular base is $\pi r^2 = \pi(7^2) = 49\pi\, \text{m}^2$.Total surface area $= 700\pi + 49\pi = 749\pi\, \text{m}^2$.Answer:The total surface area of the pipe is $749\pi\, \text{m}^2$, which is option A.