# 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? (Use π = 3.14 and take √(1.04) = 1.02)

Given

Radius of cone, r = diameter/2 = 40/2 cm = 20cm = 0.2 m

Height of cone, h = 1m

Find out

We have to find the cost of painting all these cones

Solution:

Slant height, l2 = r+ h2

On substituting the given values, l2 = (0.22+12)

= (1.04)

l = 1.02

Slant height of the cone (l) = 1.02 m

Curved surface area of each cone = πrl

= 3.14×0.2×1.02

= 0.64056

Curved surface area of 50 such cones = (50×0.64056) = 32.028

Curved surface area of 50 such cones = 32.028 m2

Also given Cost of painting 1 m2 area = Rs 12

Cost of painting 32.028 m2 area = Rs (32.028×12)

= Rs. 384.336

= Rs.384.34

Therefore, the cost of painting all the cones is Rs. 384.34.