A bakery charges $0.10 for a cookie that is 2 inches in diameter. If the price is proportional to the area, how much do they charge for an extra large cookie that is 8 inches in diameter? Assume that each cookie is shaped of a circle.
A: $0.40
B: $0.80
C: $1.60
D: $6.40
the diameter of the large cookie is 4 times that of the smaller cookie.
The area is proportional to the square of their diameter, (or their radii)
so the larger one is 16 times the area, thus it should cost 16 times the smaller, or 80 cents.
B would be my choice.