On December 31, 2015, Martin Corp invested in Marlins 5-year, $200,000 bond with a 5% interest rate for $191,575. The bond pays semiannual interest on June 30^th and December 31^st. The fair values of the bonds at the end of 2016~2018 are $194,500, $194,200, and $195,750. Martin sold its investment in Marlins bond on July 1, 2019 at 98 (i.e. selling price is = 98.5% of the face value).

show the equation used to find the market rate

1. What is the market interest rate for Marlins bond?