3. A parking garage owner requires snow removal at her garage. The number of days per year requiring snow removal is shown in the table below. Contracting for snow removal cost $500 per day. She can purchase snow removal equipment for $40,000. Useful life is 10 years, no salvage value. Operating and maintenance costs are $14,000 annually and MARR is 10% # OF DAYS 20 PROBABILITY 0.15 0.15 COST $10,000 $20,000 $30,000 $40,000 $50,000 40 60 80 100 0.35 0.30 0.05 a. Determine the mean of the PW of savings resulting from the purchase of snow removal machinery. b. Determine the standard deviation of the PW of savings resulting from the purchase of snow removal machinery. Assume that the PW is normally distributed, what is the probability of a positive PW if the machinery is purchased. C