30 ml paint is required to paint a circular plate of 20 cm radius. How much paint is required to paint a similar plate of radius 80 cm?

Correct option is B

Given:
Paint required for a plate of radius 20 cm = 30 ml
Radius of the larger plate = 80 cm
Formula Used:
For similar circular plates, the amount of paint required is proportional to the area.
Area of a circle is proportional to the square of its radius.
Paint required ∝ (Radius)²
Solution:
Let required paint for larger plate = x ml
Then,
​$$\frac{x}{30} = \frac{80^2}{20^2} \\\ \\\frac{x}{30} = \frac{6400}{400} = 16 \\\ \\x = 30 \times 16 = 480\, \text{ml}$$​​