The side of square is increased by 20%, what is the increase in perimeter?

20%

a = side of square

Perimeter of a square = 4a

*The ratio between old side and new side of a square = The ratio of perimeter of old and new square*

⇒ 20% = \(\frac{1}{5}\)           

                    old       :      New

Side:              5        :        6

Perimeter:     4×5    :      4×6 =   5   :    6

Therefore, perimeter also increased by 20%.