The timekeeper for a particular mile race uses a stopwatch to determine the finishing times of the racers. He then calculates that the mean time for the first three finishers was 5.75 minutes. After checking his stopwatch, he notices to his horror that the stopwatch begins timing at 45 seconds rather than at 0, resulting in scores each of which is 45 seconds too long. What is the correct mean time for the first three finishers?