Step-by-step explanation:
Number of people who uses the gym and the track, and also uses the pool = Number of people who use all 3 facilities = 6. (given)
Number of people who uses the gym and the track, and may or may not use the pool = 19. (given)
Therefore number of people who use the gym and track, but do not use the pool = 19 - 6 = 13.
Probability = (13/19) * 100% = 68.4%.