# Project #50199 - Statistics

MAT 152 – Statistical Methods I
Checkpoint Quiz 6
Chapter 7

1. Complete the following statements using the name and/or the symbol for the name…

1. The best point estimate for the population proportion, which is denoted by, _______________, is the ______________________________, which is denoted by, _______________.

2. The best point estimate for the ______________________________, which is denoted by, , is the ______________________________, which is denoted by, _______________.

3. The sample mean, which is denoted by, _______________, is the best point estimate for the ______________________________, which is denoted by, _______________.

4. The ______________________________, which is denoted by, _______________, is a biased estimator of the ______________________________, which is denoted by, .

2. Suppose a simple random sample of likely voters showed that 49% planned to vote for recognizing same-sex marriage. The margin of error is 3% with a 95% confidence level.

1. Using a carefully worded sentence, report the 95% confidence interval for the percentage of voters who plan to support the recognition of same-sex marriage.

2. Is there evidence that recognizing same-sex marriage will not pass?

3. Suppose the survey was taken on the streets of Winston-Salem and the measure was a North Carolina statewide measure. Explain how that would affect your conclusion.

1. In a simple random sample of 1200 Americans age 20 and over, the proportion of diabetes was found to be 0.115 (or 11.5%). Assume that the requirements are satisfied.

1. What is the standard error for the estimate of the proportion of Americans ages 20 or over with diabetes?

2. Construct and report the 95% confidence interval of the estimate for the proportion of all Americans age 20 and over with diabetes.

3. What are the critical value and the margin of error, using a 95% confidence level, for estimating this proportion?

1. According to the Centers for Disease Control, nationally, 10.7% of all Americans age 20 or over have diabetes. Does the confidence interval support or refute this claim? Explain.

1. In a Gallup Poll, 441 of 507 adults said it was “morally wrong” to clone humans.

1. What proportion of the respondents believed it was morally wrong to clone humans?

2. Assuming the Gallup Poll used a simple random sample; find a 95% confidence interval for the population proportion that believes it is morally wrong to clone humans.

3. Find a 99% confidence interval for the population proportion that believes it is morally wrong to clone humans.

4. Which interval is wider? Why?

2. A polling agency is deciding how many voters to poll.

1. The agency wants to estimate the percentage of voters in favor of extending tax cuts, and wants the margin of error of no more than 1.8 percentage points. Using 95% confidence, how many respondents must the agency poll?

2. If the margin of error is to be no more than 1.7%, with 95% confidence, should we increase or decrease the sample size? Explain.

3. If the degree of confidence were lowered to 90%, with a margin of error no more than 1.8%, would that require an increase of decrease in sample size? Explain.

3. A clinical trial was conducted to test the effectiveness of the drug zopiclone for treating insomnia in older subjects. Before treatment with zopiclone, 16 subjects had a mean wake time of 98.9 minutes. After treatment with zopiclone, the mean wake time was 102.8 minutes with a standard deviation of 42.3 minutes.

1. Assuming that the 16 subjects came from a population that was normally distributed, construct and report the 95% confidence interval for the mean wake time for a population with zopiclone treatments.

1. What are the critical value and the margin of error for estimating this mean?

1. Listed below are the ages (years) of randomly selected racecar drivers from NASCAR.

 32 32 33 33 41 29 38 32 33 23 27 45 25 29

1. Check the requirements needed to construct a 95% confidence interval for the mean age of racecar drivers in NASCAR. Note: You will need to attach the check for normality since the sample size is less than 30.

2. Assuming that the 14 subjects came from a population that was normally distributed, construct and report the 95% confidence interval for the mean age of racecar drivers in NASCAR.

3. What is the best point estimate for the mean age of racecar drivers in NASCAR?

4. What are the critical values and the margin of error for estimating the mean?

1. You want to estimate the mean SAT score of all college applicants. Use the range rule of thumb to make an estimate of the standard deviation of those scores. Possible SAT scores range from 600 to 2400. Use the estimated standard deviation to determine the minimum sample size corresponding to 95% confidence interval and a margin of error of 25 points.

1. Listed below are speeds (mph) measured on eastbound traffic on I-40 near Winston-Salem.

 67 65 70 65 73 79 62 75 71 66 69 63

1. Assuming that the data came from a normally distributed population, use the sample data to construct and report a 90% confidence interval estimate of population standard deviation.

2. What are the critical values and the margin of error for the estimating the standard deviation?

1. You want to estimate the standard deviation for the population of waiting times at McDonald’s drive-thru windows. You want to be 95% confident that the sample standard deviation is within 10% of the population standard deviation. What is the minimum sample size needed?

 Subject Mathematics Due By (Pacific Time) 12/03/2014 05:00 pm
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