Question

Please solve this question. Add in brainlist

Answer 1

Given, the length of a roller is 40 cm and its diameter is 21 cm.

Now, radius of the roller r = 21/2 cm

Now, lateral surface area = 2*π*r*h

                                         = 2*(22/7)*(21/2)*40        {height = length = 40 cm}

                                         = (22/7)*21*40

                                         = 22*3*40

                                         = 2640 cm2

Now, area of the room = lateral surface area *number of revolutions

                                 = 2640*300

                                 = 792000 cm2

                                 = 792000/(100*100)                 {since 1 cm2 = 1/(100*100) m2}

                                 = 7920/100

                                 = 79.29 m2 

                                 ≈ 79.2 m2