Answer:
$ 40.6 to make the 50 rolls of toilet paper
Step-by-step explanation:
We have that the diameter of every cylinder is 4.75 inches, therefore the gap would be that value minus the thickness of the paper, like this:
4.75 - 1.7 = 3.05
3.05 inches would be the diameter of the hole.
Now, to know the volume of the paper, we would have to calculate the total volume and then subtract the volume of the hole.
First we calculate the radii:
r = d / 2
r1 = 4.75 / 2
r1 = 2.375 in
r2 = 3.05 / 2
r2 = 1.525 in
Now if we calculate the volumes
Total volume:
Vt = pi * (r ^ 2) * h
Vt = 3.14 * (2,375 ^ 2) * 3.9
Vt = 69.08 in ^ 3
Hollow volume
Vh = 3.14 * (1,525 ^ 2) * 3.9
Vh = 28.48 in ^ 3
We subtract:
Vt - Vh = 69.08- 28.48 = 40.6
40.6 in ^ 3 would be the volume of the toilet paper
We need to know what it costs to create 50, we know it costs $ 0.02 per cubic inch
Then it would be:
40.6 * 0.02 = 0.812
In other words, making one costs $ 0.812, so making 50 would cost:
0.812 * 50 = 40.6
In other words, it costs $ 40.6 to make the 50 rolls of toilet paper
