Boomi covered a cord around a circular pipe with a radius of 4 cm and cut the cord to the required length. She then wrapped it around a 4 cm square box. How much cord is left?

Given, 

The radius of a circular pipe = 4 cm

Side of a square = 4 cm

The perimeter of the circular pipe = 2πr (Where π = 3.14).

                                                   = 2 × 3.14 × 4 = 25.12 cm

The perimeter of the square = 4 × side of the square

                                          = 4 × 4 = 16 cm

Then, the length of cord left with Boomi = Perimeter of circular pipe – Perimeter of a square

= 25.12 – 16

= 9.12 cm

Therefore, the cord left with Boomi is 9.12 cm.