Question

A roll of paper towels is 11 inches high and 6 inches in diameter. If a 300- square inch sheet of plastic is provided to wrap the paper towels, how much extra plastic is there ?

Answer 1

36.1 in²

Explanation:

The total surface area of a cylinder of height h and radius r is given by ...

SA = 2πr² + 2πrh = 2πr(r+h)

For a cylinder of height 11 inches and radius 3 inches, the surface area is ...

SA = 2π(3 in)(3 in +11 in) = 84π in² ≈ 263.9 in²

Then the "extra" wrap area is ...

300 in² -263.9 in² = 36.1 in²