Amanufacturer produces crankshafts for an automobile engine. the crankshafts wear (inches) is of interest because it is likely to have an impact on warranty claims. a random sample of 15 shafts is tested and the sample mean wear is computed to be 2.78 inches. it is known that the population standard deviation is equal to 0.90 inches and that wear is normally distributed. if you were to do a hypothesis test using the data from this problem to determine if the population mean wear is not equal to 3 inches, which test statistic would you need to use?