Question

the diameter of a roller 120 cm long is 84 CM if it takes 500 complete Revolution to level a playground determine the cost of levelling at rupees 25 per metre square​

Answer 1

Step-by-step explanation:

Clearly the roller is a right circular cylinder of height h=120 cm

and radius of its base =r=42 cm

∴ area covered by the roller in one revolution = curved surface area of the roller

=2×

7

22

×42×120cm

2

=31680cm

2

so, area covered by the roller is 500 revolution = (31680×500)cm

2

=

100×100

31680×500

m

2

=1584m

hence , cost of levelling the playground = 1584×

100

30

=Rs475.20