6.2.4 WP An article in Technometrics ["Validation of Regres- sion Models: Methods and Examples" (1977, Vol. 19(4), p. 425)] presented the following data on the motor fuel octane ratings of several blends of gasoline: Construct a stem-and-leaf display for the data. Interpret the plot. Calculate the median and quartiles of these data using Miscrosoft Excel without using mathematical formulas, except like summation and mathematical operations. Verify these values with ones obtained via MINITAB. Interpret them. 88.5 91.1 88.2 91.8 89.8 94.7 86.7 88.5 88.4 92.7 84.3 93.4 93.3 92.6 93.3 90.1 96.1 87.4 93.7 86.7 89 89.6 91.1 96.5 91 89.8 90.4 90.5 84.3 90.9 91.6 91.6 100.3 93.2 89.9 90.3 90.7 87.6 88.6 91.8 90 88.6 92.7 88.7 89.7 91.5 88.3 87.9 92.7 92.2 89.9 94.2 93 89.3 98.8 85.3 94.4 91 88.3 90.1 90.4 87.5 90.4 89.3 91.2 87.8 91.2 91.1 86.7 88.3 90.6 92.2 94.2 89.2 92.2 83.4 90.8 92.3 87.7 91 90.1 88.9