The Penn State Post office has 40 delivery trucks. From time to time, each truck fails and goes in for repair. The repair show can only work on 3 trucks simultaneously. On a daily basis, only 30 trucks are used at most, but if fewer trucks are available, then trucks are rented to bring the number up to 30. (1) Model the number of functional trucks at time t. (2) Provide the transition probability matrix P of the corresponding DTMC approximation. (3) Provide the generator matrix A Which of the following statements is true? Multiple Choice The activity variance for a variable expense will usually equal zero. The activity variance for a variable expense will be unfavorable if the actual level of activity is less than the planned level of activity The activity variance for a variable expense will be unfavorable if the actual level of activity is greater than the planned level of activity. The activity variance for a variable expense can be favorable or unfavorable depending on whether the actual expense incurred is greater than or less than the planned expense