The file P02_13.xlsx contains the thickness (in centimeters) of 252 mica pieces. A piece meets specifications if its thickness is between 7 and 15 centimeters. a. What fraction of mica pieces meets...

The file P02_13.xlsx contains the thickness (in centimeters) of 252 mica pieces. A piece meets specifications if its thickness is between 7 and 15 centimeters. a. What fraction of mica pieces meets specifications? b. Are the empirical rules for standard deviations at least approximately valid for these data? Can you tell, or at least make an educated guess, by looking at a histogram of the data? c. If the histogram of the data is approximately bellshaped and you want about 95% of the observations to meet specifications, is it sufficient for the average and standard deviation to be, at least approximately,11 and 2 centimeters, respectively?