Question

A wooden toy is in the form of a sphere with diameter 28 cm. Find the cost of polishing its surface at the rate of 50 paise per cm². (Take ∏ = 22/7)

• A. ₹1234
• B. ₹1232
• C. ₹1236
• D. ₹1230

Answer 1

Answer:

B. ₹1232

Diameter = 28 cm ⇒ Radius ( r = 14 ) cm

Surface area of sphere

$\text{Surface Area} = 4\pi r^2$

$= 4 \times \frac{22}{7} \times 14 \times 14$

$= 4 \times \frac{22}{7} \times 196$

$= 4 \times 22 \times 28 = 2464 \text{ cm}^2$

Cost of polishing

Rate = 50 paise per cm² = ₹0.50 per cm²

$\text{Cost} = 2464 \times 0.50 = 1232$

Final Answer: ₹1232