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 1 m. If the outer side of each of the cones is to be painted and the cost of painting is Rs. 12 per m2, what will be the cost of painting all these cones?

Answer 1

Answer:

384.34

Step-by-step explanation:

Radius of the cone (r) = 40/2 cm = 20 cm = 0.2 m

Height of the cone (h) = 1 m

Let l  be the slant height of a cone.

∴ l = √h2 + r2 

⇒ l = √12 + 0.22 

⇒ l = √1.04 

⇒ l = 1.02 m

Rate of painting = ₹12 per m2 

Curved surface of 1 cone = πrl m2

                                         = (3.14 × 0.2 × 1.02) m2

                                         = 0.64056 m2

Curved surface of such 50 cones = (50 × 0.64056) m2

                                                                 = 32.028 m2

Cost of painting all these cones = ₹(32.028 × 12)

                                                   = ₹384.34

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