Question

The diameter and length of a roller are 70 cm and 100 cm respectively,. It moves once over to level a playground of area 4400 m.sq. Find the number of revolutions the roller will take to level the playground

Answer 1

The roller in shape of cylinder
it's length consider as hieght
daimeter is 70 and radius is 35cm
so, it's curved surface area is
=2πrh
=2×22×35×100/7
=22000 cm²

so in m²
=22000/100 m²
=220 m²

if it roll full one time it covers 220 m² area of playground
so,
1:?::220:4400
=4400/220
=20

so it will take 20 revolutions to level the playground

Answer 2

1 . curved surface area of roller   =     2pie *r*H
                                                     =2*22/7*35*100
                                                      =22000 cm .sq
                                                        =2.2 m.sq

area of ground  = 4400 m.sq
1 revolution cover =2.2 m.sq
how many revolution  =4400/2.2
                                   2000 revolution     . answer