Continuing to use the data in Exercise 1, consider once again only the nonzero observations. Suppose that the sampling mechanism is as follows: y∗ and another normally distributed random variable z have population correlation 0.7. The two variables, y∗ and z, are sampled jointly. When z is greater than zero, y is reported. When z is less than zero, both z and y are discarded. Exactly 35 draws were required to obtain the preceding sample. Estimate μ and σ.