Although the link between obesity and one's physical condition is common knowledge, a research team stated that less was known about the relationship between obesity and one's mental state of mind (Fontaine et al, 1996). A well-established survey measuring social function (the extent of your physical health or emotional problemsinterfere with your social activities) was administered to 312 obese people. The survey has population standard deviation of 22.3. The sample mean on social function was 77.10. Round all values to the tenths. (C9)

a)Is this a t-interval or a z-interval? How do you know?

b)Construct the 99% confidence interval. (low end, high end)

c)If the U.S. population has mean social function score of 83.5, does it appear that those who are obese experience the same level of social functioning as those who are not obese? Support your answer by referencing the interval and the findings.