Question

The circumference of a circular swimming pool is 100 feet. If the radius of the pool is doubled, what will the new circumference be?

Answer 1

The new circumference is 200

Answer 2

Circumference, C= 2πr

Solve for r
C = 2πr
100 = 2πr
100/2π = r
15.92 ft = circumference of circle with C = 100ft

Doubled radius
15.92(2) = 31.83 ft = new radius
C of new circle = 2πr
C = 2π(31.83)
[C = 200 ft]
= Circumference of new circle with doubled radius.