12. Show the first moment of the uniform distribution of a random variable X is given by u = a+B 2 when a and B are the lower and upper bound of its domain respectively. 13. Assume that one-hour CO (carbon monoxide) concentration in air samples from Seoul have an approximately exponential distribution with mean 3.6 parts per million. If a policymakers in Seoul proposes a traffic control program which will reduce the mean to 2.5 parts per million, how much will the probability that the CO concentration exceeds 9 parts per million change