Over a span of 170 years, the men's world record for the mile run was reduced from 4 minutes and 56 seconds in 1804 to Roger Bannister's 3:59.4 in 1954 to John Walker's 3:49.4 in 1975. The graph records times. by years and suggests that a straight line provides a good fit. A time-series regression produces the equation t 16.473 .0064Y, where t is the time in minutes (i.e., t = 4.1 means 4 minutes and 6 seconds) and Y is the year.

a. According to the equation, the passing of each decade should reduce the record by how many seconds?

b. Steve Cram's 1985 world record was 3:46.32. Hichman El Guerouj holds the current world record of 3:43.13 set in 1999. How accurate is the equation's forecast for each of these times?

c. What is the predicted world record time for 2010? Would it be reasonable to use the equation for 2050?