What was his average swimming speed during the second half of the race if he tied the record, which was at an average speed of 2.05 m/s?

I believe this question has additional detail which stated that during the 1st half, his speed was 2.01 m/s. From this we can calculate his speed during the second half, v2, using the formula:

v_ave = (v1 + v2) / 2

2.05 m/s = (2.01 m/s + v2) / 2

v2 = 2.09 m/s