In order to bid for a nonstandard construction job. an engineer needs to estimate the duration, D, of the project. Since no prior information on similar jobs is available, the engineer estimates that it may take 10 to 20 days. Suppose the PDF of D can be defined by a uniform distribution between 10 and 20 days. Define the PDF of D. Define the CDF of D. Calculate the mean of D. Calculate the variance, standard deviation, and coefficient of variation of D. Calculate the skewness and skewness coefficient of D. Calculate the modal and median values of D