Question

the diameter of a roller 120cm long is 84cm if it takes 500 complete Revolution to level a playground determine the cost of levelling it at the rate of 45 paise per square metre

Answer 1

Diameter=84cm
therefore radius=42cm
height=120cm
area rolled in 1 revolution=c.s.a 
=2*22/7*r*h=2*22/7*42*120
316800 cm^2 = 3.168 m^2
area of field=500*3.168
=1584 m^2
cost=30 p/m^2
therefore, total cost=1584*30
47520 p/m^2

Answer 2

Diameter=84cm
therefore radius=42cm
height=120cm
area rolled in 1 revolution=c.s.a 
=2*22/7*r*h=2*22/7*42*120
316800 cm^2 = 3.168 m^2
area of field=500*3.168

=1584 m^2
cost=30 p/m^2
therefore, total cost=1584*30
47520 p/m^2
4.3