When Pope John Paul II died in April 2005 after serving 27 years as pontiff, newspapers reported years of tenure of popes through the ages, starting with St. Peter, who reigned for 35 years (from 32 to 67 A.D.). Tenures of all 165 popes averaged 7.151 years, with standard deviation 6.414 years. A test was carried out to see if tenures of the eight 20th-century popes were significantly longer than those throughout the ages. Explain why a z test is carried out instead of t.