ReviewforTest3F09.pdf

# ReviewforTest3F09.pdf - Review for Test 3 YOU NEED TO KNOW...

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Review for Test 3 YOU NEED TO KNOW 1. Confidence Interval for the mean when σ is known (know the conditions, the formula, and how to interpret them) 2. Confidence Interval for the mean when σ is unknown (know the conditions, the formula, and how to interpret them) 3. how to find the margin of error 4. how to find the sample mean and the margin of error if the CI is given 5. how the CIs behaves as we increase the confidence, or we change the sample size 6. how to find the minimum sample size when the margin of error is given 7. how to carry out a hypothesis test for the mean (check conditions, state claims, find the test statistic, find the p-value, give the conclusion) 8. which test to use for the mean: the z-test, or the t-test 9. how to find the sample proportion 10. large-sample confidence intervals for a proportion (know the conditions, the formula, and how to interpret them) 11. how to find the minimum sample size when the margin of error is given (for proportions) 12. how to carry out a hypothesis test for the proportion (check conditions, state claims, find the test statistic, find the p-value, give the conclusion) 13. how to carry out a hypothesis test to compare two population means or proportions (state the claims, find the test statistics, find the p-value, give the conclusion) 1. From a random sample of 36 days in a recent year, the closing stock prices of Hasbro had a mean of \$19.31. From past studies we know that the population standard deviation is \$2.37. a. Should you use the z -distribution, or the t -distribution to construct a CI for the population mean for closing stock prices of Hasbro? b. Construct the 90% and 95% confidence intervals for the population mean. Interpret the CIs. c. Which interval is wider? What are the margins of errors? 2. You randomly select 20 mortgage institutions and determine the current mortgage interest rate at each. The sample mean rate is 6.93% with a sample standard deviation of 0.42%. Find the 99% confidence interval for the population mean mortgage interest rate. Assume the interest rates are approximately normally distributed. (t* = 2.861) 3. A biologist reports a CI of (2.1cm, 3.5cm) when estimating the mean height of a sample of seedlings. Find the sample mean and the margin of error.

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