48 A more extensive tabtulation of t critical values than wh

48. A more extensive tabtulation of t critical values than what appears in this book shows that for the t distribution with 20 df, the areas to the right of the values. 687, .860, and 1.064 are .25, .20, and . 15, respectively. What is the confidence level for each of the following three confidence intervals for the mean Mu of a normal population distribution? Which of the three intervals would you recommend be used, and why?

Solution

Answer.

The correct recommendation is c)

the interval is defined as (x bar - t s/ sqrt(n) , x bar + t s/ sqrt(n))

This is fulfilled in option c