Question

a roller 140 cm long has a radius of 35 cm .to level the playground it takes 980 complete revolutions. determine the cost of levelling the playground at the rate of 75 paisa per square metre.

Answer 1

first we need to find the surface area of the roller
LSA=2πrh
=2x22÷7x35x140 =30800cm^2 or 3.08m^2
so 1 revo = 30800cm
980 = ?
30800x980=
30184000cm^2 or
3018.4m^2
so 3018.4x75=226380 or ₹ 2263.80

Answer 2

Surface area of roller=2πrl =2π×35×140 30787 Total area=30787*980 30171855 Cost 0.75*30181855 Rs22628891