The pH scale measures the amount of alkalinity or acidity in a liquid and ranges from 0-14. The ideal pH for a swimming pool is 7.2. A pH that is too high or low can cause discomfort for the swimmers, especially in the eyes.
High variability in the pH readings across the swimming pool can be problematic. The following data shows seven pH readings that were taken at the Wilson Community Pool from different locations at 10 A.M. this morning.7.0 6.9 7.2 7.1 7.4 7.4 7.3The pool management would like to test the hypothesis that the standard deviation of the pH readings across the pool is less than 0.40. The sample standard deviation is ________.A) 0.195
B) 0.240
C) 0.297
D) 0.358
Question 2
A recent study reported that 18- to24-year-olds averaged 192 restaurant visits per year. Assume that the standard deviation for number of visits per year for this age group is 56.5.
To validate these findings, a random sample of forty 18- to 24-year-olds was selected and found to average 212 restaurant visits per year. Which of the following statements is correct?A) The interval that contains 95 of the sample means is 170.3 and 213.7 visits. Because the sample mean is between these two values, we have support for the results of the May 2011 study.
B) The interval that contains 95 of the sample means is 170.3 and 213.7 visits. Because the sample mean is between these two values, we do not have support for the results of the May 2011 study.
C) The interval that contains 95 of the sample means is 174.5 and 209.5 visits. Because the sample mean is not between these two values, we have support for the results of the May 2011 study.
D) The interval that contains 95 of the sample means is 174.5 and 209.5 visits. Because the sample mean is not between these two values, we do not have support for the results of the May 2011 study.
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