3. A new water line must be constructed from an existing pumping station to a reservoir. Estimates of construction and pumping costs for each pipe size have bee Pipe Size n made 8" 10" 12" The annual cost is based on a 16-year life and a desired rate of return of 10%. which is the most economical pipe size for pumping 4000 hr/year? Estimated Construction Cost/hour of pumping Costs $80,000 $100,000 $160,000 $4.00 $3.00 $1.50