A random sample of nine telephone calls in an office provided the following information. Duration Call Number (In Minutes) Type of Call 9 local 2 long distance 4 local 4 local 12 long distance 5 6 local 7 14 local 7 long distance 9 local a. Determine the point estimate for the average duration of all calls rounded to three decimal places. b. What is the point estimate for the standard deviation of the population rounded to three decimal places? c. Determine the standard error of the mean rounded to three decimal places. d. What is the point estimate for the proportion of all calls that were local rounded to three decimal places? e. Determine the standard error of proportion rounded to three decimal places