ANSWER

4:26

60 feet for 40 minutes -> Group G
Looking at Table 3, using the 50 foot row, looking at the bottom number going from right to left, until we find a number that is 50 minutes or larger, we see that the diver must be a group B diver before she can do this dive safely.
Using the Surface Interval Table, to go from Group G to Group B takes 4 hours and 26 minutes