2) We test 50 American children and find that average level of cholesterol of the sample is 198. We know the population standard deviation is 15. It is known that the mean cholesterol level for all Americans is 190.

a) Do we have evidence to suggest that American children have an average higher cholesterol level than the national average? (Use a 0.05 level of significance).

b) At the 0.05 level of significance, use the p value approach.

c) Interpret the meaning of the p value.

4) 50 smokers were questioned about the number of hours they sleep each day. The sample mean is 7.5 and standard deviation is 0.5. Is there evidence that the smokers need less sleep than the general public which needs an average of 7.7 hours of sleep (=0.05).

6) A recent survey in a town showed that most of people support candidate A in the local election. The poll of 500 adults was conducted and 400 of them supported candidate A. Perform the hypothesis test at 10% level of significance to find out whether the fraction of people will support candidate A in the next election will be more than 75%.