Question

Radius of a sphere is 70mm.find the cost of painting the curved surface@Rs. 0.02 per cm2.

Answer 1

Curve surface area of sphere is

$4\pi {r }^{2}$

radius of sphere is 70 mm;

surface area = 4*3.14*70*70;

=61544sq.mm;

now converting this into sq.cm;

1 Cm = 10 mm;

61544 sq.mm = 615.44 sq.cm;

Per square. cm cost is = 0.02;

total cost of painting = 615.44*0.02 = Rs. 12.3