solve each part

3. (Textbook #82) The lifetime X (in hundreds of hours) of a type of vacuum tube has a Weibull distribution with parameters a = 2 and = 3. (a) Find the probability that such a vacuum tube lasts between 400 and 500 hours, i.e., find P(4.= X = 6). (b) Find the probability that such a vacuum tube lasts at least 500 hours. (c) Find E(X), expressed in exact form, and with a decimal approximation. (d) Find V(X), expressed in exact form, and with a decimal approximation. (e) Derive a formula for the (100p)th percentile of X (in terms of p)