Question

1. The production line for Glow toothpaste is designed to fill tubes with a mean weight of 6 oz. Periodically, a sample of 30 tubes will be selected in order to check the filling process. Quality assurance procedures call for the continuation of the filling process if the sample results are consistent with the assumption that the mean filling weight for the population of toothpaste tubes is 6 oz.; otherwise the process will be adjusted.

Assume that a random sample of 30 toothpaste tubes provides a sample mean of 6.1 oz. The population standard deviation (σ) is believed to be 0.2 oz.

1. Perform a hypothesis test, at the 0.03 level of significance, to help determine whether the filling process should be stopped and corrected. (Hint: because you know σ, you will use the Z table to find the critical value(s)).

2. Calculate the 97% confidence interval.

Answer 1