Quick Answer:

The second race will end in a tie.

Complete Solution:

In the first race, Exponent ran 45 meters in the same time it took Polygon to run 50 meters. In the second race, the finish line is 45 meters from Exponent’s starting position and 50 meters from Polygon’s. Therefore, if each runs at the same speed as in the previous race, the race will end in a tie.