The article “How Business Students Spend Their Time—Do They Really Know?” (Research in Higher Education Journal [May 2009]: 1–10) describes a study of 212 business students at a large public university. Each student kept a log of time spent on various activities during a 1-week period. For these 212 students, the mean time spent on Facebook was 1.06 hours and the standard deviation was 2.01 hours. Suppose that this sample was a random sample from the population of all business majors at this university and that you are interested in learning about the value of m, the mean time spent on Facebook for this population. The following table is similar to the table that appears in Example 12.4. The “what you know” information has been provided. Complete the table by filling in the “how you know it” column.
What You Know
The sampling distribution of  is centered at the actual (but unknown) value of the population mean.
An estimate of the standard deviation of , which describes how the  values spread out around the population mean m, is 0.138.
The sampling distribution of  is approximately normal.
How You Know It