Final answer:
Gustavo would likely infer that Indy 500 drivers are generally under the age of 50 because success in the sport may be correlated with faster response times, which younger individuals tend to have.
Step-by-step explanation:
Gustavo, after reading that the winners of the Indy 500 range in age from 22 to 47 and thinking about his background knowledge of race car driving, would most likely make the inference that Indy 500 drivers are under 50 because younger people respond faster. This is suggested by the age range of the winners, which might imply that successful drivers tend to be those who still have quick reflexes and reaction times, which can diminish with age.