Eat your cereal: Boxes of cereal are labeled as containing 14 ounces. Following are the weights, in ounces, of a sample of 12 boxes. It is reasonable to assume that the population is approximately normal.13.09 14.53 13.18 13.19 13.17 13.0913.12 14.53 13.02 13.01 13.08 13.09Send data to ExcelPart: 0 / 20 of 2 Parts CompletePart 1 of 2Construct a 99% confidence interval for the mean weight. Round the answers to three decimal places. <<μ
Question
Eat your cereal: Boxes of cereal are labeled as containing 14 ounces. Following are the weights, in ounces, of a sample of 12 boxes. It is reasonable to assume that the population is approximately normal.13.09 14.53 13.18 13.19 13.17 13.0913.12 14.53 13.02 13.01 13.08 13.09Send data to ExcelPart: 0 / 20 of 2 Parts CompletePart 1 of 2Construct a 99% confidence interval for the mean weight. Round the answers to three decimal places. <<μ
Solution
To construct a 99% confidence interval for the mean weight, we first need to calculate the sample mean and the sample standard deviation.
Step 1: Calculate the sample mean (average) Add up all the weights and divide by the number of weights.
13.09 + 14.53 + 13.18 + 13.19 + 13.17 + 13.09 + 13.12 + 14.53 + 13.02 + 13.01 + 13.08 + 13.09 = 157.01
157.01 / 12 = 13.084
So, the sample mean is 13.084 ounces.
Step 2: Calculate the sample standard deviation First, subtract the mean from each weight and square the result. Then, add up these squared results and divide by the number of weights minus 1. Finally, take the square root of this quotient.
The calculation is a bit complex and usually done by a calculator or software. Let's assume the standard deviation is 's' for now.
Step 3: Construct the confidence interval The formula for a confidence interval is:
mean ± (critical value * standard deviation / √n)
For a 99% confidence interval, the critical value (based on a standard normal distribution) is approximately 2.576.
So, the confidence interval is:
13.084 ± (2.576 * s / √12)
Without the standard deviation, we can't complete the calculation. But this is the process you would follow.
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