Math CentralQuandaries & Queries


Question from keith:

how many yds of paper for a roll with a width of 6.875 and a core of 3 in and a diameter of 40in?


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!


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