Question

Circle A has a diameter of approximately 20 inches and an area of approximately an area of 300 in² Circle B has a diameter of approximately 60 inches Which of these could be the area of circle B? A. About 100 in^2 B. About 300 in^2 C. About 900 in^2 D. About 2700 in^2

Answer 1

D. About 2700 in^2

Explanation:

The area of a circle A = πd²/4 where d = diameter of circle.

A/d² = π/4 = k the proportionality constant.

So, A₁/d₁² = A₂/d₂² Now for circle A, Area = A₁ = 300 in² and diameter = d₁ = 20 inches. For circle B, Area = A₂ = unknown and diameter = d₂ = 60 inches.

So, we have

A₁/d₁² = A₂/d₂²

A₂ = A₁d₂²/d₁²

A₂ = A₁(d₂/d₁)²

substituting the values of the variables, we have

A₂ = 300 in²(60 in/20 in)²

A₂ = 300 in²(3)²

A₂ = 300 in²(9)

A₂ = 2700 in²

So, the area of circle B is about 2700 in²