4. For a 1-year project, the yearly sales volume (X) is uncertain. The estimated mean of the sales volume is 200, and the variance is 1089. The net cash flows are given in terms of X MARR - 10% a. Determine an equation for the present worth in terms of x. b. Determine the mean (a) and standard deviation (a) of the NPW. Period Net Cash Flow D -$4,000 1 $55X - $1,650