Asked Nov 24, 2019

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 216 days. After a revised mix has been developed, a sample of nine boxes of cake mix gave these shelf lives (in days): 215, 217, 218, 219, 216, 217, 217, 218, and 218. Using α = 0.025, has the shelf life of the cake mix increased?


Expert Answer

Step 1

The hypotheses used for testing are given below:

Step 2

The sample statistics used for testing the significance are given below:


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Mean 215 217+218+,..., +217+218+218 9 =217.22 Thus, the mean shelf life of cake mix for the given sample is 217.22 days. Standard deviation: Σr-3) п-1 11.6 = =1.20 Thus, the standard deviation for the shelf life of cake mix for the given sample is 1.20 days

Step 3

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Test statistic: t = 217.22-216 1.20 3.66 1.20 =3.05 Thus, the test statistic is 3.05.


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