A national survey claims that the average time adults spend on exercise is 45 minutes per day. A fitness researcher suspects that members of a specific gym spend more time than this. She takes a random sample of 64 gym members and finds their mean daily exercise time is 48.5 minutes with a standard deviation of 12 minutes. Test, at the 5% level of significance, the researcher's claim. State your hypotheses clearly.
130 exam-style questions on AQA A Level Maths 2.5.3 Hypothesis test for a Normal mean (A-level only). Each one has a worked solution and a mark scheme showing where the marks go.