Question

  1.The diameter of a sphere is 28 cm. Find the cost of painting it all around at Rs. 0.10 per square cm.

Answer 1

it's easy just find SA of sphere & then multiply by cost given

Answer 2

Solution :-

The diameter of a sphere is 28cm

As we know that ,

Radius = Diameter / 2

Radius = 28/2

Radius = 14cm

Thus, The radius of the sphere is 14cm

As we know that,

Total Surface area of sphere = 4πr^2

Put the required values,

TSA of sphere

= 4 * 22/7 * 14 * 14

= 4 * 22 * 2 * 14

= 4 * 44 * 14

= 4 * 616

= 2464cm^2

Thus, The TSA of the sphere is 2464cm^2

Now,

Cost of painting per cm^2 = 0.10

Therefore,

The cost of painting 2464 cm^2

= 0.10 * 2464 = Rs

Hence, The total cost of painting the sphere it all around is Rs 246.4..