1) A random sample of 18 purchases showed the amounts in the table? (in $). The mean is ?$46.81 and the standard deviation is ?$24.47
?a) What is the standard error of the? mean?
?b) How would the standard error change if the sample size had been 2 instead of 18?? ?(Assume that the sample standard deviation? didn't change.)
41.93 22 34.63 30.6 81.76 24.31 45.63 66.27 47.3 28.26 68.55 28.82 85.41 51.08 72.09 13.25 86.31 14.44
2) Find the critical value t* for the following situations.
?a) a 95?% confidence interval based on df=2.
?b) a 98?% confidence interval based on df = 61.
View the? t-table.