posted by Anonymous .
2. The Occupational Safety and Health Administration (OSHA) estimates that roughly 30% of all worker compensation claims stem from back injuries. This statement was made many years ago and you want to know if this has changed in recent years. Suppose you take a random sample of 200 claims and find that 45 of them relate to back injuries.
You can try a proportional one-sample z-test for this one since this problem is using proportions.
Using a formula for a proportional one-sample z-test with your data included, we have:
z = .225 - .30 -->test value (45/200) is .225) minus population value (.30) divided by
√[(.30)(.70)/200] --> .70 represents 1-.30 and 200 is sample size.
Finish the calculation. I'll let you take it from here.