The mean waiting time at the drive through of a fast food
Last updated: 12/10/2023
The mean waiting time at the drive through of a fast food restaurant from the time an order is placed to the time the order is received is 87 6 seconds A manager devises a new drive through system that he believes will decrease wait time As a test he initiates the new system at his restaurant and measures the wait time for 10 randomly selected orders The wait times are provided in the table to the right Complete parts a and b below Click the icon to view the table of correlation coefficient critical values Critical values Sample Size n Critical Value 5 0 880 0 888 0 898 0 906 0 912 0 918 0 923 0 928 0 932 0 935 0 939 a Because the sample size is small the manager must verify that the wait time is normally distributed and the sample does not contain any outliers The normal probability plot is shown below and the sample correlation coefficient is known to be r 0 985 Are the conditions for testing the hypothesis satisfied the conditions linear enough since the correlation coefficient is In addition a boxplot does not show any outliers 6 7 8 9 10 11 12 13 14 15 satisfied The normal probability plot Sample Size n 16 17 18 19 20 21 22 23 24 25 30 than the critical value Critical Value 0 941 0 944 0 946 0 949 0 951 0 952 0 954 0 956 0 957 0 959 0 960 X A Expected z score 2 101 5 67 6 57 6 75 1 66 1 1 0 60 75 90 105 80 4 96 84 9 70 8 Time sec 79 3