ANSWER : 1 hour

52 feet for 44 minutes -> Group H
Group H on the surface for 1:45 ->E
Group E at 47 feet  max time -> 32 (so 32 minutes is o.k.).  Residual Nitrogen time is 38 minutes.  Add RNT (residual nitrogen time) to ABT (actual bottom time) of 32 to get 70 minutes.  47 feet for 70 minutes makes the diver a Group I diver. 

Now we look at table 3 to see what group she needs to be before she can dive to 38' for 50 minutes.  Look at the 40 foot row and going from right to left, find a number bigger than or equal to 50 on the bottom row.  We find 57 in the G column.  So she must be a G before she can do this dive.  To go from I to G takes 1 hour (from table 2)