Question

16
3) A cylindrical tube has an outer diameter of 2.5
cm and an inner diameter of 1.5 cm. Its length is
7 cm. If it has to be anti-rust coated on the outer
side, the inner side and the rims on both sides,
what is the total surface area to be covered for
this purpose? Calculate the cost if the rate is
20.50 per cm?​

Answer 1

Answer:

Step-by-step explanation:

Surface area of outer side = 2π r h

                                        = 2π x 2.52×72.52×7

                                      = 17.5π cm2

Surface area of inner side = ​2π r h  

                                        = 2π×1.52×7×1.52×7

                                      = 10.5π cm2

Area of rim on both sides = π (router−rinner)2router-rinner2

                                       = π​×(2.52−1.52)2×2.52-1.522

                                     = π4π4 cm2

Total surface area = 17.5π + 10.5π + 2 π4π4

                           = 28.5π

                          = 89.57 cm2

Cost = 89.57 x 0.5 = Rs. 44.785