Mortgage Rates The average 30-year fixed mortgage rate in the United States in the first week of May in 2010 through 2012 is approximated by 55.9 M(t) = 0.31t+11.2 percent per year. Here t is measured in years, with t = 0 corresponding to the first week of May in 2010.+ (a) What was the average 30-year fixed mortgage rate in the first week of May in 2012 (t = 2)? (Round your answer to two decimal places.) % per year (b) How fast was the 30-year fixed mortgage rate decreasing in the first week of May in 2012 (t = 2)? (Round your answer to two decimal places.) % per year