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Confidence Interval

Statistics: Solving for the Confidence Interval

Question: A sample of 20 pages was taken without replacement from the 1,591 page phone directory Ameritech Pages Plus Yellow Pages. On each page the mean area devoted to display ads was measured (a display ad is a large block of multicolored illustrations, maps, and text). The data (in square millimeters) are shown below: 0

Confidence Interval

What does it mean when you apply confidence intervals using a normal distribution?

Significance Tests and Confidence Intervals

Please help with the following problem. Using the data on the table below, are there any correlations between population changes for the areas listed. The following is a list of acceptable tests: regression line and equation; correlation one-sample t-test one-sample t confidence interval matched-pairs t-test two-sa

Statistics - 3. A sample of 49 households is taken from a population in which the standard deviation is 7. The standard error of the mean isPlease see the attached file. 4. It is desired to construct a 95% confidence interval. The correct value of Z to obtain for the 95% confidence interval is: ... 5. A confidence interval has been constructed with total width of 50 units. If the sample mean is 100, the lower bound of the interval is ... [See the attached questions file.]

3. A sample of 49 households is taken from a population in which the standard deviation is 7. The standard error of the mean isPlease see the attached file. 4. It is desired to construct a 95% confidence interval. The correct value of Z to obtain for the 95% confidence interval is: ... 5. A confidence interval has been const

Statistics: Proportions and Confidence Interval

Never forget that even small effects can be statistically significant if the samples are large. Of 148 small businesses, 106 were headed by men and 42 were headed by women. During a three-year period, 15 of the men's businesses and 7 of the women's businesses failed. a) Find the proportions of failures for businesses headed

Confidence Interval

A manufacturer would like to estimate the average number of copies that can be made from a single bottle of toner. A random sample of 20 bottles was selected for this experiment. For the 20 bottles of toner the average number of pages was 1535 with a standard deviation of 50 pages. a) Compute the 95% confidence interval f

Confidence interval samples

A sample of n=16 scores is obtained from an unknown population. The sample has a mean of M=46 with SS=6000. a. Use the sample data to make an 80% confidence interval estimate of the unknown population mean. b. Make a 90% confidence interval estimate of μ. c. Make a 95% confidence interval estimate of μ.

50. Use the following information to construct the confidence intervals specified to estimate µ 51. A sample of size n = 10 is randomly selected from a normal population with mean µ = 52 and variance σ2 = 22.5. The sample value X-bar is calculated.

50. Use the following information to construct the confidence intervals specified to estimate µ a) 95% confidence; = 25, σ2 = 12.25, and n = 60. b) 98% confidence; = 119.6, S2 = 570.7321, and n = 75. c) 90% confidence; ∑X = 1814.4, σ2 = 0.948676, and n = 32. 51. A sample of size n = 10 is randomly sel

Testing of Hypothesis and Confidence Interval.

1. A random sample of 500 measurements on the length of stay in hospitals had sample mean 5.4 days and sample standard deviation 3.1 days. A federal regulatory agency hypothesizes that the average length of stay is in excess of 5 days. a. Do the data support this hypothesis? Use  = 0.05. b. Construct a 98% confiden

Statistics - Confidence Interval for a Random Sample

1. a) A random sample of 100 managers in Alaska had an average yearly income of $125,500 with a standard deviation of $20,000. Develop the 95%, 90%, and 99% confidence intervals for the yearly income of all managers in Alaska. b) If we assume we know the standard deviation of yearly income of all managers in Alaska is $25,00

Statistics confidence interval

Jennifer wants to find a 95% confidence interval for the time it takes her to get to work. She kept records for 30 days and found her average time to commute to work was 20.5 minutes with a standard deviation of 3.9 minutes. What is Jennifer's maximum error of estimate in minutes?

Confidence interval - Malfunctioning Equipment

You decide to measure the time between equipment malfunctions over a one-year period. Over that time you measured 40 electronic products. You made 850 observations with a mean time between equipment failures of 550.35 hours, and a sample standard deviation of 207 hours. Your company supplies the electronic product to anoth

Confidence interval for average height of US Navy recruits

A US Navy recruiting center knows from past experience that the height of its recruits are normally distributed with mean 68 inches. The recruiting center wants to test the claim that the average height of this year's recruits is greater than 68 inches. To do this, recruiting personnel take a random sample of 64 recruits from th

Statistics

Sample of 20 pages was taken out replacement from the 1,591 page directory. On each page the main areas devoted to display ads was measured. The data is square millimeters are shown 0 260 356 403 536 0 268 369 428 536 268 396 469 536 162 238 403 536 536 130 a) Construct a 95 per cent confidence intervals for the true mea

Confidence interval for average annual for retail sales

Assume the population standard deviation is 3.8 thousand dollars. 4.4 6.5 4.2 8.9 8.7 8.1 6.1 6.0 2.6 2.9 8.1 -1.9 11.9 8.2 6.4 4.7 5.5 4.8 3.0 4.3 -6.0 1.5 2.9 4.8 -1.7 9.4 5.5 5.8 4.7 6.2 15.0 4.1 3.7 5.1 4.2 a) Verify that for the data, x(x bar)=5.1, find 8

Confidence Interval and Hypothesis Testing - 2. A sample of 81 observations is taken from a normal population. The sample mean is 40, and the sample standard deviation of 5. Determine the 95 percent confidence interval for the population mean. 3. Merrill Lynch Securities and Health Care Retirement, Inc, are two large employers in down ... [See the attached Quesstions File]

2. A sample of 81 observations is taken from a normal population. The sample mean is 40, and the sample standard deviation of 5. Determine the 95 percent confidence interval for the population mean. 3. Merrill Lynch Securities and Health Care Retirement, Inc, are two large employers in down Toledo, OH. They are considering joi

Level and Width of Confidence Interval of Mean

Directions: 1) Calculate a point estimate and a 95% confidence interval of the mean. Assuming your data set is normally distributed, determine an appropriate sample size if the maximum allowable error is three units for the attached data set. (Please note: the three units are measure in the unit of measurement of the attache

2. The following table classifies 800 telephone calls by type (local or long distance) and by length: (6 points) a. What is the probability that a call sampled at random out of this population is local and 1 -5 minutes long? b. What is the probability that a call sampled at random is long distance? c. What is the probability that a call is not 5+ minutes given that is a long distance call?

Please answer the following questions in Microsoft Excel. There are six questions total. Work on how to do it should be shown. 2. The following table classifies 800 telephone calls by type (local or long distance) and by length: (6 points) a. What is the probability that a call sampled at random out of this population is l

Confidence Interval and Probability

4) A building developer has the opportunity to purchase several acres of land that is divided up into several lots for building single-family homes. It is known that the average sale price of all of the lots is $80,000 and the standard deviation of the sale price is $12,000. What can you say about the percentage of lots that ha

Confidence Interval

Explain why a confidence interval for a predictor coefficient is equivalent to a 2-tailed test of significance?

Confidence interval for mean number of hours for batteries

For a random sample of 10 fifth generation iPod music players, the mean battery life was 9.47 hours with a standard deviation of 2.14 hours. a. Construct a 95% confidence interval for the mean number of hours the batteries will last on these players. b. Suppose you wanted more accuracy, what could you do to increase the

Confidence interval for the mean number of books read

A survey conducted during May 20 - 22, 2005, asked 1006 Americans, "During the past year, about how many book, either hardcover or paperback, did you read either all or part of the way through?" Results of the survey indicated that the mean of the sample was 13.4 books with a standard deviation of 16.6 books. Construct a 99% c

Confidence Interval

1. The following sample of 16 measurements was selected from a population that is approximately normally distributed: 91 80 99 110 95 106 78 121 106 10 97 82 100 83 115 104. Construct a 95% confidence interval for the population mean. 2. In a survey of 1000 persons, 290 responded that they approve of the president's job perfo

Please see the Attachment for all the 11 Questions.

1) The diameter of Ping- Pong balls manufactured at a large factory is expected to be approximately normally distributed with a mean of 1.30 inches and a standard deviation of 0.40 inch. What is the probability that a randomly selected Ping-Pong ball will have a diameter between 1.31 and 1.33 inches? A) 0.0987 (B) 0.1747 (C) 0.

Critical value, confidence level

Please see the attached file. 1. What is the appropriate critical value for each of the following confidence levels and sample sizes? (Remember that in regard to confidence level this implies two-tails) (a) Critical z-value for an 85% confidence level for sample of size n = 36: (b) Critical t-value for