Math Problem Statement
You measure 25 backpacks' weights, and find they have a mean weight of 30 ounces. Assume the population standard deviation is 8.8 ounces. Based on this, what is the maximal margin of error associated with a 99% confidence interval for the true population mean backpack weight.
Give your answer as a decimal, to two places
Solution
To calculate the maximal margin of error for the 99% confidence interval, we can use the formula for the margin of error in a confidence interval when the population standard deviation is known:
Where:
- is the Z-value corresponding to the confidence level (99% in this case),
- is the population standard deviation,
- is the sample size.
Step 1: Find the Z-value
For a 99% confidence level, the Z-value corresponds to the critical value that leaves 0.5% of the probability in each tail (because 1% is split between the two tails of the normal distribution). The Z-value for 99% confidence is approximately 2.576.
Step 2: Plug the values into the formula
- Population standard deviation ounces,
- Sample size .
Final Answer:
The maximal margin of error is approximately 4.53 ounces.
Would you like more details on how this formula works or any further clarifications?
Additional Questions:
- How do you determine the Z-value for different confidence levels?
- What happens to the margin of error if the sample size increases?
- How does the margin of error change when you use a sample standard deviation instead of the population standard deviation?
- How would the margin of error be affected if the population standard deviation were larger?
- What is the purpose of a confidence interval in statistics?
Tip:
When working with confidence intervals, it's always important to check if you know the population standard deviation. If not, you'll need to use the t-distribution instead of the normal distribution.
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Math Problem Analysis
Mathematical Concepts
Confidence Intervals
Margin of Error
Normal Distribution
Z-Score
Formulas
Margin of Error = Z_{\alpha/2} × σ / √n
Theorems
Central Limit Theorem
Z-Distribution for Known Standard Deviation
Suitable Grade Level
Grades 10-12
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