During construction of the surface layer of asphalt pavement, two samples where taken everyday to measure the asphalt content in the mix to ensure that it is within the specification limits.the target value was set at 5.5 percent with a tolerance of -+ 0.4 percent. the following asphalt content data were collected:
a) Calculate the mean, standard deviation, and the coefficient of the variation of the data.
b)Using a spreadsheet program, create a control chart for these data showing the target value and the upper and lower specification limits. comment on any trend and possible reasons.