She curled an 8 inch by 10 inch rectangular piece of paper to form an open cylinder. A height of that cylinder is h = 10 in. Then 8 inches will represent the circumference of the base of the cylinder ( or the circumference of the circle, which represents the base ). Therefore: C = 2 r π, or: 8 = 2 r π. Now we can also calculate the radius of the base:
r = 8 : 2 π = 8 : 2 * 3.14 = 8 : 6.28 ≈ 1.27 in.
Answer: 8 inches will be the circumference of the base of the cylinder.