Facebook: A study showed that two years ago, the mean time spent per visit to Facebook was20.1

minutes. Assume the standard deviation is= 7.0 minutes. Suppose that a simple random sample of103 visits was selected this year and has a sample mean of= x 22.1 minutes. A social scientist is interested to know whether the mean time of Facebook visits has changed. Use the= 0.05

level of significance and the critical value method with the table.

(a) State the appropriate null and alternate hypotheses.

(b) Compute the value of the test statistic.

(c) State a conclusion. Use the= 0.05 level of significance.