Facebook : A study showed that two years ago, the mean time spent per visit to Facebook was 20.8 minutes. Assume the standard deviation is=σ10.0 minutes. Suppose that a simple random sample of...

Facebook: A study showed that two years ago, the mean time spent per visit to Facebook was 20.8 minutes. Assume the standard deviation is=σ10.0 minutes. Suppose that a simple random sample of 103 visits was selected this year and has a sample mean of =x23.8 minutes. A social scientist is interested to know whether the mean time of Facebook visits has changed. Use the =α0.05 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 =α0.05 level of significance.