Answer Happy

A manufacturer the formula of cake mix. Past records indicate that the average shelf life of the current formula is 216 days. Assume that cake mix is distributed normally with a population standard deviation of 4.00 .A revised mix has been developed and the sample mean of 25 boxes of cake mix using the new formula is 218. Using a = 0.10, has the shelf life of the cake mix changed? 1) No, because computed z lies in the region of acceptance. 2) No, because 218 is quite close to 216. 3) Yes, because computed z is greater than the critical value. 4) Yes, because computed z is less than the critical value.