In Exercise 5.16, Y1 and Y2 denoted the proportions of time that employees I and II actually spent working on their assigned tasks during a workday. The joint density of Y1 and Y2 is given by f (y1, y2) = y1 + y2, 0 y1 1, 0 y2 1, 0, elsewhere. In Exercise 5.80, we derived the mean of the productivity measure 30Y1 + 25Y2. Find the variance of this measure of productivity. Give an interval in which you think the total productivity measures of the two employees should lie for at least 75% of the days in question.

A pool measuring 14 meters be 16 meters is surrounding by the path of uniform width, as shown in the ﬁgure....