A metal pipe is 77cm long. The inner diameter of a cross section is 4cm, the outer diameter being 4.4cm (see figure). Find its (i) Inner curved surface area. (ii) Outer curved surface area (iii) Total surface area

Given:Inner radius=4/2=2cm=r1Outer radius=4.4/2=2.2cm=r2Height=77cmSolution:(i) Curved Surface Area=2πr1h(inner)=2×22/7×2×77=968cm2(ii) Outer Curved Surface Area (outer)=2πr2h=2×22/7×2.2×77cm2=(22×22×2.2)cm2=1064.8cm2(iii) Total Surface Area of pipe=CSA of inner surface+CSA of outer surface+Area of circular base and top=968+1064.8+2π((2.2)2−(2)2)=2032.8+2π(4.84-4)=2032.8+2π(0.84)=2032.8+2×22/7×0.84=2032.8+5.28cm2=2038.08cm2