steel cable barriers on highway medians are a low-cost way to improve traffic safety without busting state department of transportation budgets. there are two mutually exclusive alternatives: cable barriers cost $44,000 per mile, compared with $55,000 per mile for guardrail. furthermore, cable barriers tend to snag tractor-trailer rigs, keeping them from ricocheting back into same-direction traffic. the state of ohio spent $4,972,000 installing 113 miles of cable barriers. (a) if the cables prevent accidents totaling $1.1 million per year, determine the rate of return that this represents over a 10-year study period. use a spreadsheet. (b) now, determine the rate of return for 113 miles of guardrail if accident prevention is $1.3 million per year over a 10-year study period. (c) conduct incremental ror analysis to determine the more economical alternative. assume the marr is 10% per year.