The director of Human Resources at a large company wishes to determine if newly instituted training has been effective in reducing work-related injuries. In a random sample of 100 employees taken from the six months before this training began (group 1), she found 15 had suffered a work-related injury. Using a random sample of 150 employees from the six months since the training began (group 2), she found 12 had suffered a work-related injury. a. Find the 95% confidence interval for this situation.
b. Does it support the idea that the proportion of work-related injuries has decreased with the new training?