Your parents bought you a used car for your seventeenth birthday and you want to know how many miles to a gallon the car gets You kept records for the miles you drove each time you filled up the tank with gas For the first forty tanks of gas you had a mean of 29 5 miles per gallon with a standard deviation of 4 9 Using the table below find the 90 confidence interval 28 23 to 30 77 O27 981 to 31 02 O27 50 to 31 50 Confidence Level as a percent G 90 95 99 z value 1 645 1 960 2 576