please solve with formulas like (F/P, 5% , n) not with the excell.

B.6. A small city is experiencing rapid growth and has taken on a number of new city employees over the past several years in new service areas such as traffic, planning, recreation, and so on. The one operator at the city hall manual switchboard can no longer handle all the calls, and the telephone company offers the following alternatives for service for the next 10 years (use i = 7% and, for simplicity, use n = 10 yr rather than 120 months). 1. Add a second operator. Each operator gets $880 per month ($10,560/yr), including fringe benefits. This salary is expected to increase by $50 per month each year for each operator ($600/yr). A second manual switchboard would cost $12,000 plus $100 per month ($1,200/yr) service charges for each switchboard. The existing switchboard service could be sold for $1,000 if not continued in service. 2. Install an automatic system for $65,000 plus $600 per month ($7,200/yr) on a 10-year service contract. Assume zero salvage value. 417 CHAPTER 14 Benefit/Cost Analysis (a) Find the modified B/C ratio. (Hint: Consider alternative 1 as the existing system and alternative 2 as the proposed. All operating expenses are either M, or M) (b) Does the conventional B/C equation give valid results? Why? (e) Can the rate of return method be used to compare these alternatives? Why? B.6. A small city is experiencing rapid growth and has taken on a number of new city employees over the past several years in new service areas such as traffic, planning, recreation, and so on. The one operator at the city hall manual switchboard can no longer handle all the calls, and the telephone company offers the following alternatives for service for the next 10 years (use i = 7% and, for simplicity, use n = 10 yr rather than 120 months). 1. Add a second operator. Each operator gets $880 per month ($10,560/yr), including fringe benefits. This salary is expected to increase by $50 per month each year for each operator ($600/yr). A second manual switchboard would cost $12,000 plus $100 per month ($1,200/yr) service charges for each switchboard. The existing switchboard service could be sold for $1,000 if not continued in service. 2. Install an automatic system for $65,000 plus $600 per month ($7,200/yr) on a 10-year service contract. Assume zero salvage value. 417 CHAPTER 14 Benefit/Cost Analysis (a) Find the modified B/C ratio. (Hint: Consider alternative 1 as the existing system and alternative 2 as the proposed. All operating expenses are either M, or M) (b) Does the conventional B/C equation give valid results? Why? (e) Can the rate of return method be used to compare these alternatives? Why