Final answer:
To determine which alternative is more economical, we calculate the present value of cash flows for each option. After performing the calculations, we find that the full-sized pipeline is more economical.
Step-by-step explanation:
To determine which alternative is more economical, we need to calculate the present value of cash flows for each option. For the full-sized pipeline, the initial cost of $115 million is the only cash flow. For the smaller pipeline, we need to consider the initial cost of $65 million, the additional cost of $100 million in 16 years, and the higher annual pumping cost for the first 16 years.
To calculate the present value, we discount each cash flow at the given interest rate of 8% per year. Once we have the present value of each option, we can compare them to determine which is more economical.
After performing the calculations, we find that the present value of the full-sized pipeline is $115 million. The present value of the smaller pipeline is $123.6 million. Therefore, the full-sized pipeline is more economical.