Given: Radius of cone, r = diameter/2 = 40/2 cm = 20cm = 0.2 m Height of cone, h = 1m Slant height of cone is l, and l2 = (r2+h2) Using given values, l2 = (0.22+12) = (1.04) Or l = 1.02 Slant height of the cone is 1.02 m Now, CSA of each cone = πrl = (3.14×0.2×1.02) = 0.64056 CSA of 50 such cones = (50×0.64056) = 32.028 CSA of 50 such cones = 32.028 m2 Again, Cost of painting 1 m2 area = Rs 12 (given) Cost of painting 32.028 m2 area = Rs (32.028×12) = Rs.384.336 = Rs.384.34 (approximately) Therefore, the cost of painting all these cones is Rs. 384.34.