1.A manufacturer of bedding wants to do quality control on its 400-thread-count sheets. The thread count varies normally with a mean thread count = 400 and a standard deviation = 8. A quality control researcher randomly selects 16 sheets and finds that the mean thread count for the sample is 395.2.

In this problem, we have made slight changes to the "sheet thread count" story in previous questions. In which of the following options is the change such that it would be inappropriate to conduct a hypothesis test (e.g., z-test for the population proportion, z-test for the population mean, or t-test for the population mean) for H₀: = 400 vs. H_a: = 400? Check all that apply.

1. A manufacturer of bedding wants to do quality control on its 400-thread-count sheets. The thread count has a mean thread count = 400 and a standard deviation = 8. A quality control researcher randomly selects 16 sheets and finds that the mean thread count for the sample is 395.2.
2. A manufacturer of bedding wants to do quality control on its 400-thread-count sheets. The thread count has a mean thread count = 400 and a standard deviation = 8. A quality control researcher randomly selects 50 sheets and finds that the mean thread count for the sample is 395.2.
3. A manufacturer of bedding wants to do quality control on its 400-thread-count sheets. The thread count varies normally and has a mean thread count = 400. A quality control researcher randomly selects 16 sheets and finds that the mean thread count for the sample is 395.2 with a standard deviation of 8.
4. A manufacturer of bedding wants to do quality control on its 400-thread-count sheets. The thread count has a mean thread count = 400. A quality control researcher randomly selects 16 sheets and finds that the mean thread count for the sample is 395.2 with a standard deviation of 8.