Keith,

You need to know the thickness of the paper to be able to answer this.
The outer and inner radii are 20 and 1.5 in
The cross sectional area is
pi*(20² - 1.5^5) in²
= pi*(400-2.25) in²
= pi *397.75 in²
= 1250 in² to four decimal places.
Divide this by the thickness of the paper to get the length L in inches.
(Divide L by 36 to get the length in yards)

Multiply L by 6.875 to get the area A in square inches.
(Divide A by 36² = 1296 to get the area in square yards.)

Good Hunting!
RD