If the side of a square increases by 20%, then what will be a percent increase in its perimeter?

Question

Question

This question was previously asked in

SSC GD Previous Paper 2 (Held On: 11 Feb 2019 Shift 2)

Answer 1

Given:

Let the side of the square be x

And Perimeter of square = 4x

Formula Used:

Perimeter of square = 4 × (side)

Area of Square = (side)²

Area of Circle = π × (radius)²

Perimeter of Circle = 2 × π × (radius)

Concept :

If sides increase by 20%. So Perimeter also increases by 20%

Sides become 1.2 times original

So, Perimeter becomes 4 × 1.2 = 1.2 times original

Alternative solution:

Let the side of the square be 100 cm

Side of the square is increased by 20% becomes = 100 + 100 × 20/100

⇒ 120 cm

Perimeter before increase = 4 × 100 = 400 cm

After 20% increased = 4 × 120 = 480 cm

Increase in percentage = [(480 - 400)/400]× 100

⇒ 20%

Mistake PointsPlease attention there asks the Perimeter, not the area, mostly students mark the 44% suppose to the area, but ask the perimeter.