2. Let $X_{1}, X_{2}, \ldots, X_{n}$ be a random sample from $X$ which follows an exponential distribution with parameter $\theta$. a. Show that $\bar{X}$ is consistent estimator of $\theta$. (18) b. Show that $\bar{X}$ is sufficient statistics of $\theta$. c. Find the mean and the variance of $X$. SP.DL.1971