4. Let Xi be a random variable from a uniform distribution on the interval [0,b]. Thus the lower bound is known but not the upper bound. You observe 73, many independent and identically dis- 7 n tributed Xi's. What is the expected value of the sample mean X = iii-Xi? How could you i=1 transform X to make it an unbiased estimator of b (that is to say the expectation of the estimator is equal to b)