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   
160 - 1691
170 - 17916
180 - 18971
190 - 199108
200 - 2091
210 - 21918
220 - 2293


What is the upper class limit for the fourth class?

upper class limit =