Question

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

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$.$

Answer 2

$\huge{\bf{\green{\mathfrak{Question:-}}}}$

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

$\huge {\bf{\orange{\mathfrak{Answer:-}}}}$

• Diameter of the given sphere = 28 cm.

• Radius = $\large{\frac{28}{2}}$ = 14 cm.

• Total Surface area of a sphere = 4πr².

• 4πr²

• $\large{4 \: * \: \frac{22}{7} \: * \: 14 \: * \: 14}$

• $\textsf{4 \: * \: 22 \: * \: 2 \: * \: 14}$

• $\boxed{\textsf{2464 \: cm²}}$

• Cost of painting 1 cm² = ₹ 0.10

• Cost of painting 2464 cm² = 2464 * 0.10

• $\boxed{\textsf{₹ \: 246.4}}$

$\huge{\bf{\red{\mathfrak{Conclusion:-}}}}$

• $\boxed{\therefore{\textsf{Cost \: of \: painting \: a \: sphere \: of \: diameter \: 28 \: cm \: = \: ₹ \: 246.4}}}$

$\huge{\bf{\purple{\mathfrak{Extra \: Information:-}}}}$

• TSA of sphere = 4πr².

• Volume of sphere = $\large{\frac{4}{3}πr²}$