+ Given that z is a standard normal random variable, compute the following probabilties. a) Compute the mean and standard deviation to use as estimates of the population mean and standard deviation. -1 Mean (H): a) P( z = -1): b) What is the probability that, on a randomly selected day, the early morning trading volume will exceed 180 million shares? C) Z: -15 X: 180 P(z= -15): c) What is the probability that, on a randomly selected day, the early morning trading volume will exceed 230 million shares? d) Z: X 230 P( Z 230 ): P( z