ANSWER : Group I

52 feet for 42 minutes -> Group H
Group H on the surface for 2:10 ->E
Group E at 48 feet  max time -> 32 (so 27 minutes is o.k.).  Residual Nitrogen time is 38 minutes.  Add RNT (residual nitrogen time) to ABT (actual bottom time) of 27 to get 65 minutes.

48 feet for 65 minutes ->I
I out for 4 hours ->C;    C at 42 feet can stay 49 minutes (so 41 is o.k.).  RNT is 21 minutes.  Add to actual bottom time of 41 minutes to get 62.  42 feet for 62 minutes results in group I.