The mean length of a candy bar is supposed to be 43 millimeters. there is 3) concern that the settings of the machine cutting the bars have changed. test the claim at the .02 level that there has been no change in mean length. the alternate hypothesis is that there has been a change. twelve bars (n = 12) were selected at random and their lengths in millimeters are: 42, 39, 42, 45, 43, 40, 39, 41, 40, 42, 43, and 42. the mean length of the sample is 41.5. the sample standard deviation is 1.784. the population standard deviation is not known. if the computed t = −2.913, has there been a statistically significant change in the mean length of the candy bars?