Answer Happy

7) A manufacturer wants to increase the shelf life of a line of cake mixes. Past records indicate that the average shelf life of the mix is 233 days. After a revised mix has been developed, a sample of nine boxes of cake mix gave these shelf lives (in days): 231,236, 237, 238, 235, 242, 242, 243, and 239. Using a -0.025, has the shelf life of the cake mix increased? A) Yes, because computed t is greater than the critical value. B) Yes, because computed t is less than the critical value. C) No, because computed t lies in the region of acceptance. D) No, because 238.11 is quite close to 233.