28. The San Andreas Fault A geologist studying the movement of the earth’s crust at a particular location on California’s San Andreas fault found many fractures in the local rock structure. In an attempt to determine the mean angle of the breaks, she sampled n550 fractures and found the sample mean and standard deviation to be 39.88 and 17.28, respectively. Estimate the mean angular direction of the fractures and find the margin of error for your estimate.