Proportional Circles

An artist is making a circular stained glass window with a diameter of 10 in. The stained glass costs $4.50 per square inch. To the nearest dollar, what will be the total cost of the stained glass for the artist's entire window?

• $31

• $79

• $353

• $1413

The Jones family wants to enclose their circular garden with a fence. To the nearest foot, what is the minimum length of fencing they need to buy?

• 56.25 ft

• 246 ft

• 365 ft

• 393 ft

A bicycle tire has a diameter of 27 inches. How far does the bike travel along the ground when the wheel rotates once?

• 84.78

• 15.5

• 27

• 13

Shring's dining room table is round and has a radius of 4.5 feet. What is the tabletop's area?

• 63.585 ft²

• 68.345 ft²

• 64.585 ft²

• 61.345 ft²

What is the constant of proportionality of the circumference to the radius?

• 2π, or 6.28

• It depends on the measurements.

• They are not proportional.

• π, or 3.14

Answer explanation

Since we have to double the radius to get the diameter, the constant of proportionality between circumference and the radius is 2π.

The ratio of the radii of two circles is 4:9. What is the ratio of their circumferences?

• 2:3

• 4:9

• 16:81

The ratio of the circumference of a circle to the diameter

• distance

• pi

• radii

• diameter

Which shows the ratio for pi?

• circumference to diameter

• radius to circumference

• area to diameter

• area to radius

What is the constant of proportionality? Remember to simplify your answer.

• m = 9

• m = 10

• m = 90

• m = 10/9

• m = 1

Determine the radius of the penny

• 59.66 mm

• 9.5 mm

• 38 mm

• 119.32 mm