Question

A bus stop is barricaded from the remaining part of the road, by using 50 hollow cones made of recycled cardboard. Each cone has a base diameter of 40 CM and height 1m. If the outer side of each of the cones is to be painted and the cost of painting is ₹12 per m2, what will be the cost of painting all these cones? ( Use 3.14 and take √1.04=1.02)​

Answer 1

Answer:

Curved surface area of cone will be painted=πrl

h=1m;radius= 40/2 =20cm=0.2m

and let l be the slant height,

∴l^2 =h2+r2 =1^2 +0.2^2

⇒l= √1+0.04 = √1.04=1.02m (∵ √1.04=1.02 is given in the question)

⇒Curved surface area of 1 cone=πrl=(3.14×0.2×1.02)m2 =0.64046m2

⇒ Curved surface area of 50 cones=50×0.64046=32.028m2

Cost of painting 1m2 =Rs.12

∴ Cost of painting 32.028m2

=(12×32.028)=384.336m2 ≈384.34

∴ Cost of painting 50 cones is Rs.384.84

Hope this is helpful for you.