Confidence Interval Worksheet - Grade 11 Math
This worksheet covers key concepts of confidence intervals, including calculation, interpretation, and impact of sample size and confidence level.
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Confidence Interval Practice
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Read each question carefully and answer to the best of your ability. Show all your work for calculation problems.
1. What does a 95% confidence interval mean?
There is a 95% probability that the true population parameter lies within the interval.
If we were to take many samples and construct a confidence interval for each, about 95% of these intervals would contain the true population parameter.
95% of the sample data falls within the interval.
The sample mean is 95% accurate.
2. Which of the following will decrease the width of a confidence interval?
Increasing the confidence level.
Decreasing the sample size.
Decreasing the population standard deviation.
Increasing the sample size.
3. The is the range of values within which the population parameter is expected to lie with a certain level of confidence.
4. As the sample size increases, the margin of error tends to .
5. A confidence level will result in a wider confidence interval, assuming all other factors remain constant.
6. A random sample of 60 students from a large university was taken. The average GPA of these students was 2.95 with a standard deviation of 0.4. Construct a 90% confidence interval for the true mean GPA of all students at the university. Assume the population standard deviation is unknown.
7. A larger margin of error provides a more precise estimate of the population parameter.
True
False
8. If the confidence level decreases, the critical value (z-score or t-score) will increase.
True
False
9. A polling organization wants to estimate the proportion of voters who support a particular candidate. In a random sample of 500 voters, 280 indicated support for the candidate. Construct a 99% confidence interval for the true proportion of voters who support the candidate.