Final answer:
The calculated value of the test statistic for whether the true mean rating is over 4, given the sample data, is approximately 1.9365.
Step-by-step explanation:
The student is asking about how to calculate the test statistic for a sample where they want to introduce a new frozen yogurt flavor. To find the test statistic for whether the true mean rating is over 4, given an average (sample mean) rating of 4.4 with a standard deviation of 1.6 from a sample of 15 customers, we use the formula for the single-sample t-test:
Z = (\bar{x} - \mu_{0}) / (s/\sqrt{n})
Where \bar{x} is the sample mean, \mu_{0} is the hypothesized population mean, s is the sample standard deviation, and n is the sample size.
Plugging in the values:
Z = (4.4 - 4) / (1.6 / \sqrt{15})
This gives us:
Z = (0.4) / (1.6 / \sqrt{15}) ≈ 1.9365
The calculated value of the test statistic is approximately 1.9365.