# The ratio of radius of two circles is 1 ∶ 4, what will be the ratio of the areas of the circle?

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The ratio of radius of two circles is 1 ∶ 4, what will be the ratio of the areas of the circle?

1. 1 ∶ 4
2. 1 ∶ 16
3. 16 ∶ 1
4. 4 ∶ 1

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Correct Answer - Option 2 : 1 ∶ 16

Given:

Ratio of the radius of the circles = 1 ∶ 4

Formula used:

Area of the circle = πr2

Calculation:

Let the radius of the circles be x and 4x units

Area of circle1 = πx2

Area of circle2 = π(4x)2

Ratio of areas = πx2 ∶ π(4x)2

⇒ Ratio of area = x2 ∶ 16x2

∴ Ratio of the area of the two circles is 1 ∶ 16