You must size a pipeline to carry crude oil at a rate of 1 million bbl/day. If the viscosity of the oil is $25 \mathrm{cP}$ and its $\mathrm{SG}$ is 0.9 , what is the most economical diameter for the pipeline if the pipe costs $\$ 3 / \mathrm{ft}$ of length and per inch of diameter, the power cost is $\$ 0.05 / \mathrm{kWh}$, and the pipeline cost is to be written off over a 3 year period? The oil enters and leaves the pipeline at atmospheric pressure. What would the answer be if the economic lifetime of the pipeline is 30 years?