For each question, indicate whether it is best assessed by using a confidence interval, a hypothesis test, or whether statistical inference is not relevant to answer it. If inference is not relevant, explain why.
(a) What proportion of people using a public restroom wash their hands after going to the bathroom?
(b) On average, how much more do adults who played sports in high school exercise than adults who did not play sports in high school?
(c) In 2010, what percent of the US Senate voted to confirm Elena Kagan as a member of the Supreme Court?
(d) What is the average daily calorie intake of 20-year-old males?