Given asphalt content test data: a. Calculate the overall mean and standard deviation for the entire test period.
b. The contract specifications require an average asphalt content of 5.5% +/-0.5% every day Plot the daily average asphalt content. Show upper and lower control limits
c. Do all of these samples meet the contract specifications? Explain your answer
d. What trend do you observe based on the data? What could cause this trend?
Date Sample Number Asphalt Content %
5-May 1 5.5
5-May 2 5.8
6-May 3 5.3
6-May 4 5.4
7-May 5 5.7
7-May 6 5.7
8-May 7 5.6
8-May 8 5.8
9-May 9 5.4
9-May 10 5.5
12-May 11 5.3
12-May 12 5.6
13-May 13 5.8
13-Ma 14 5.1
14-May 15 5.8
14-May 16 5.9
15-May 17 5.1
15-May 18 5.2
16-May 19 5.2
16-May 20 4.8