Question

the length of a roller is 40cm and its diameter is 21cm it takes 300 complete revolutions to move once over to the floor of a room find the area of the room in m^2

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 cm^2
=> (21/2)*40        {height = length = 40 cm}

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

                                     = 2640*300

                                     = 792000 cm2

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

                                     = 7920/100
 = 79.29 m^2


hope this will help......☺️

Answer 2

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