In exercise 5.10, we proved that 1, 0≤y1 ≤2,0≤y2 ≤1,2y2 ≤y1, f (y1, y2) = 0, elsewhere 0, elsewhere is a valid joint probability density function for y1, the amount of pollutant per sample collected above the stack without the cleaning device, and for y2, the amount collected above the stack with the cleaner. a if we consider the stack with the cleaner installed, find the probability that the amount of pollutant in a given sample will exceed .5. b given that the amount of pollutant in a sample taken above the stack with the cleaner is observed to be 0.5, find the probability that the amount of pollutant exceeds 1.5 above the other stack (without the cleaner).