coralsheep891

1. a) Other things being equal, as the confidence level for a confidence interval increases, the width of the interval Increases, Decreases, Stays the same, or none of the above. b) The ________________ confidence interval, the more useful information it gives us. Wider, narrower, neither. c) The midpoint of the confidence interval for the proportion is population proportion, sample proportion, a confidence level, none of the above. d) What does the confidence interval for the mean depend on? sample, mean, standard deviation, sample size, confidence level. Can be more than one.

2. A new method is developed to determine the content of sodium in a biscuit sample. Student A gets the following results: 24.2, 23.9, 25.0, 23.7 and 25.2 mg, while student B obtains 22.6, 21.9, 23.2 and 23.1 mg. (a) Report 95% confidence interval of their results individually. Why the standard deviations are non-zero? (b) At the 95% confidence level, does one of them get more reproducible measurements? (c) At the 95% confidence level, do they obtain different results? What about 90% confidence level? (d) According to the manufacturer, the sodium content in the biscuit is 24.0 mg. Comment whether student B’s results are reliable at 90% confidence level. (e) The results from student C are 25.3, 25.4, 24.9, 25.0, 23.2 and 24.5 mg. Determine whether there is an outlier at the confidence level of 95%? What about 90%?