00:01
In this problem it is said that a roll of toilet paper has a radius of 3 inches, the cardboard tube has a radius of 0 .5 inches, the roll is 4 .5 inches long.
00:10
We need to determine how much toilet paper is in the roll in cubic inches.
00:14
So for this purpose, recall the formula for the volume of a cylinder.
00:19
This is given by pi r squared h where r is the radius and h is the height.
00:26
So we want to find how much toilet paper is on the roll in cubic inches.
00:31
So what we are going to do is we are going to find the volume of the outer cylinder and from that we will subtract the volume of the inner cylinder.
00:38
This will give us the volume of the toilet paper.
00:42
So for the outer cylinder we have pi, then we have r squared.
00:46
Now the roll of toilet paper has a radius of 3 inches, so we have 3 squared...