A nutritionist wants to determine how much time nationally people spend eating and drinking. Suppose for a random sample of 1070 people age 15 or older, the mean amount of time spent eating or drinking per day is 1.71 hours with a standard deviation of 0.72 hour. Complete parts (a) through (d) below.
(a) A histogram of time spent eating and drinking each day is skewed right. Use this result to explain why a large sample size is needed to construct a confidence interval for the mean time spent eating and drinking each day.
Since the distribution of time spent eating and drinking each day is not normally distributed (skewed right), the sample must be large so that the distribution of the sample mean will be approximately normal.
(b) In 2010, there were over 200 million people nationally age 15 or older. Explain why this, along with the fact that the data were obtained using a random sample, satisfies the requirements for constructing a confidence interval.
(c) Determine and interpret a 99% confidence interval for the mean amount of time Americans age 15 or older spend eating and drinking each day. Select the correct choice below and fill in the answer boxes, if applicable, in your choice. (Type integers or decimals rounded to three decimal places as needed. Use ascending order.)
(d) Could the interval be used to estimate the mean amount of time a 9-year-old spends eating and drinking each day? Explain.
No; the interval is about people age 15 or older. The mean amount of time spent eating or drinking per day for 9-year-olds may differ.