Question

The Japanese 5 yen coin has a hole in the middle. If the diameter of the coin is 22 mm and the diameter of the hole is 5 mm, how would you calculate in terms of Pi how much longer the outer edge is than the inner edge?

Answer 1

To find the difference between the outer and inner edges of the coin, you would calculate the circumference of the coin, C= 22π, and the circumference of the hole, C = 5π. Then you would subtract to find the answer, 22π − 5π = 17π.

Step-by-step explanation: Sample answer!!

Answer 2

4.4mm

Explanation:

Circumference of circle

2 Pi r

Diameter of coin = 22mm

Therefore the radius = 11mm

Therfroe the outer edge (circumference)

= 2 Pi r

= 2 x Pi x 11

=69.11mm

For the inner edge

Diameter = 5

Radius = 2.5

Therefroe inner edge (circumference)

= 2 Pi r

= 2 x Pi x 2.5

= 15.7mm

The difference is

69.11 - 15.7

=4.4mm