Find a 90% prediction interval for the third quartile of professors with seven years of experience.

1. A full professor of statistics at a major US university is interested in estimating the third quartile of salaries for full professors with 6 years of experience in that rank. Data, in the form of the 2005-2006 Salary Report of Academic Statisticians, are available at http://www.amstat.org/profession/salaryreport_acad2005-6.pdf (accessed March 12, 2007) (Table 4.3). Using weighted least squares, estimate the 2005-2006 third quartile for salary of full professors with 6 years of experience. 2. Consider regression though the origin (i.e., straight line regression with popula