Question

A hemispherical bowl made of brass has inner diameter 10.5 cm. Find the cost of the plating it on the inside at the rate of Rs. 4 per 100 cm².

Answer 1

Answer:

The cost of painting 173.09 cm² is Rs 6.92

Step-by-step explanation:

Given as :

For hemispherical bowl

The inner diameter = d = 10.5 cm

Or, inner radius = r = $\dfrac{d}{2}$ cm

i.e  r = $\dfrac{10.5}{2}$

∴  inner radius = 5.25 cm

∵ curved surface area of hemispherical bowl = 2 × π × radius²

Or, curved surface area of hemispherical bowl = 2 × 3.14 × (5.25)²

∴ curved surface area of hemispherical bowl = 173.09 cm²

Now, According to question

The rate of painting the bowl is Rs 4 per 100 sq cm

Or, ∵ The cost of paining 100 cm² = Rs 4

Or, The cost of painting 1 cm² = $\dfrac{4}{100}$

∴ The cost of painting 173.09 cm²  = $\dfrac{4}{100}$  × 173.09

i.e The cost of painting 173.09 cm²  = Rs 6.92

Hence, The cost of painting 173.09 cm² is Rs 6.92 Answer