Math Problem Statement
What sample size should be obtained if we want to be within four percentage points with 96% confidence if we use an estimate of 48% obtained from a poll?
Solution
To determine the sample size required to achieve a specified margin of error with a given confidence level, we can use the formula for the sample size for estimating a population proportion. The formula is:
where:
- is the Z-score corresponding to the desired confidence level,
- is the estimated proportion,
- is the margin of error.
Given:
- Confidence level: 96%
- Margin of error: 4% (0.04)
- Estimated proportion (): 48% (0.48)
First, find the Z-score for a 96% confidence level. For a 96% confidence level, the Z-score corresponds to the area in the tails of the normal distribution such that 2% is in each tail (100% - 96% = 4%, so each tail has 2%).
Using a Z-table or standard normal distribution table, the Z-score for 96% confidence is approximately 2.05.
Now, plug these values into the formula:
Calculate the components step by step:
Now, compute the sample size:
Since the sample size must be a whole number, round up to the next whole number:
Therefore, the sample size required is 656.
Would you like more details or have any questions about this calculation?
Here are 8 relative questions that expand on this information:
- What is the Z-score for a 95% confidence level?
- How does the margin of error affect the sample size?
- What happens to the sample size if the estimated proportion is closer to 0.5?
- How can we determine the Z-score without a Z-table?
- What is the formula for determining sample size for a population mean?
- How does increasing the confidence level affect the required sample size?
- What is the impact of a smaller margin of error on the sample size?
- How would the sample size change if the confidence level was increased to 99%?
Tip: Always round up the calculated sample size to ensure the margin of error is not exceeded.
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Math Problem Analysis
Mathematical Concepts
Statistics
Confidence Intervals
Normal Distribution
Formulas
Sample size formula for population proportion
Theorems
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Suitable Grade Level
Advanced High School
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