4. Suppose that the lifetime of a certain type of lamp has an exponential distribution for which the value of the parameter B is unknown. A random sample of n lamps of this type are tested for a period of 7 hours and the number x of lamps that fail during this period is observed; but the times at which the failures occurred are not noted. Determine the MLE. of B based on the observed value of X
5. Suppose that XXn form a uniform distribution on the interval [a,b], where both endpoints a and b are unknown. Find the MLE. of the mean of the distribution
6. Suppose that XXn form a random sample from a normal distribution for which both the mean and the variance are unknown. Find the MLE. of the 0.95 quantile of the distribution, that is, of the point 0 such that Pr(X < 0) -0.95