A mail-order computer business has six telephone lines. Let X denote the number of lines in use at a specified time. Suppose the pmf of X is as given in the accompanying table. 2 3 4 P(X=x) 0.10 0.15...

Extracted text: A mail-order computer business has six telephone lines. Let X denote the number of lines in use at a specified time. Suppose the pmf of X is as given in the accompanying table. 2 3 4 P(X=x) 0.10 0.15 0.20 0.20 0.06 0.04 a A. Calculate the probability of each of the following events. a. {at most three lines are in use} b. {fewer than three lines are in use} c. {at least three lines are in use} d. (between two and five lines, inclusive, are in use} e. {between two and four lines, inclusive, are not in use} f. {at least four lines are not in use} B. Construct the cumulative distribution function table C. Construct histogram D. Find the E(X), V(X), standard deviation