In: Statistics and Probability
An experiment was performed to compare the abrasive wear of two different laminated materials. 40 pieces of material 1 were tested by exposing each piece to a machine measuring wear. 100 pieces of material 2 were similarly tested. In each case, the depth of wear was observed. The samples of material 1 gave an average (coded) wear of 85 units with a sample standard deviation of 4, while the samples of material 2 gave an average of 81 with a sample standard deviation of 5. Can we conclude at the 0.05 level of significance that the abrasive wear of material 1 exceeds that of material 2 by more than 2 units? Assume the populations to be approximately normal?