7 The operations manager of a plant that manufactures tires wants to compare the actual inner diameter of two grades of tires, each of which is expected to be 575 millimeters. A sample of five tires of each grade is selected and the results, representing the inner diameters of the tires, ranked from smallest to largest, are as follows: Grade X Grade Y 568 570 575 578 584 573 574 575 577 578 a) For each of the two grades of tires, calculate the mean, median and standard deviation b) which grade of tire is providing on average better quality? Explain. What would be the effect on your answers in (a) and (b) if the last value for grade y was 588 instead of 578? Explain