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. र 12 per m², what will be the cost of painting all these cones? (Use $straight pi$ = 3.14 and take $square root of 1.04 end root equals 1.02 right parenthesis$

Base diameter = 40 cm
$therefore$ Base radius (r) = $40 over 2$ cm = 20 cm

= $20 over 100 straight m equals 0.2 space straight m$
Height (h) = 1 m

$therefore space space straight l equals square root of straight r squared plus straight h squared end root space space space space space equals square root of left parenthesis 0.2 right parenthesis squared plus left parenthesis 1 right parenthesis squared end root equals square root of 0.04 plus 1 end root space space space space space equals square root of 1.04 end root space equals space 1.02 space straight m$

Curved surface area = πrl
= 3.14 x 0.2 x 1.02 = 0.64056 m²∴ Curved surface area of 50 cones = 0.64056 x 50 m² = 32.028 m²∴ Cost of painting all these cones = 32.028 x 12
= 384.336 = र 384.34 (approximately).

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