Astudy of gym members was undertaken to see if machine-users were more prone to injury than free-weight users. assume for this study that you can only be injured in the gym once in your lifetime. 1500 gym patrons across the county were polled beginning january 1, 2003. on june 5, 2003, it was discovered that 75 of those gym patrons currently had gym-related injuries. after june 5, the remaining injury-free patrons were enrolled in a cohort study, classified as machine-users (n=1000) and free-weight users (n=425), and followed for 3 years. 85 machine-users and 15 free-weight users became injured in the 3 years. all follow-up stopped on exactly june 5, 2006. assuming complete ascertainment and no drop-outs, what is the odds ratio for injury among machine users?