Data was collected for 300 fish from the North Atlantic. The length of the fish (in mm) is summarized in the GFDT below.

  Lengths (mm)     Frequency   
80 - 811
82 - 8316
84 - 8571
86 - 87108
88 - 891
90 - 9118
92 - 933


What is the class midpoint for the third class?

class midpoint =