Math CentralQuandaries & Queries


Question from Edu, a student:

I have a 12 in pipeline and 5 miles long. I need to coat it with corrosion inhibitor how much chemical will I need


The inside surface area of a cylinder is $\pi$ times the inside diameter times the length where $\pi$ is approximately 3.1416. You have a cylinder that has a diameter of 12 inches and a length of 5 miles. You need both dimensions in the same units so I am going to use feet. There are 12 inches in a foot and 5,280 feet in a mile so the inside surface of your pipeline is

\[\pi \times 1 \times 5 \times 5,280 \mbox{ square feet.}\]

I hope this helps,

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