Answer:

1.   Students should recognize that the years are changing by five-year increments. 

      This is very important in solving this question.  Depending on how students see

      this problem as a linear change or exponential change their answers can vary. 

      In 2006, using linear, the time should be about 12.7.  Using exponential models in

     2006 the time should be about 13.9.

2.   Using linear change student will say runners will break the 13-second mark in 2005.

      Using exponential change students will say runners will break the 13-second mark in 2011. 

      Students could use graphs, calculators (residual models), calculations, or other methods

      to estimate their answers.