4. A robot has just been installed at a cost of $81,000. It will have no salvage value at the end of its useful life. (Review Chapter 10) Savings per Year Probability Useful Life (years) Probability $18,000 0.2 12 1/6 $20,000 0.7 2/3 $22,000 0.1 1/6 a. What is the joint probability distribution for savings per year and useful life? b. Define optimistic, most likely, and pessimistic scenarios by using both optimistic, both most likely, and both pessimistic estimates. What is the rate of return for each scenario