In a certain noisy factory, all workers are provided with earplugs and are expected to wear them.All workers had normal hearing at their preemployment examinations when the factory opened. One year later, an industrial hygienist inspecting the plant found that 100 of the 500 workers in the factory werenotwearing their earplugs because they regarded them as uncomfortable and a nuisance. When all the workers were given a hearing test, it was found that 4 of the earplug wearers and 10 of thenonwearershad developed significant hearing loss.

What was the cumulative incidence rate of hearing loss in workers who didnotwear earplugs? (Please state your answer per 100, e.g., 2/100)

What was the relative risk of hearing loss in workers who did not wear earplugs, compared with those who did?(Hint: Incidenceof hearing loss among those who did not wear earplug is the numerator)

What was the risk of hearing loss attributable tonotwearing earplugs? (i.e., what was the risk difference?)

What proportion of hearing loss in thenonwearerswas attributable tonotwearing earplugs?

What proportion of the hearing loss inall the workerswas attributable tonotwearing earplugs?(hint: "all workers" implies population)