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Confidence Interval

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

95 & 90% Confidence Interval

A random sample taken of 1200 likely voters a week before election show that 628 of them plan on voting for Abraham Washington in the upcoming election. Calculate a 95% confidence interval and a 90% confidence interval based on this data. Then state this interval in a single sentence, explaining to Mr. Washington his chances o

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

Confidence Interval of Peak Power after Training

An article in Medicine and Science in Sports titled "Maximal Leg Strength Training" studied cycling performance before and after 8 weeks of training. Seven cyclists trained for 8 weeks; peak power increased to mean of 315 watt with a standard deviation of 16 watts. Construct a 95% confidence interval for the mean peak power a

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?

Statistics confidence interval

A food snack manufacturer samples 7 bags of pretzels off the assembly line and weighed their contents. If the sample mean is 10.4 and the sample standard deviation is 0.15, find the 95% confidence interval of the true mean.

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

Description of Confidence Intervals

Consider the given set of average annual household income levels of citizens of selected U.S. metropolitan areas in the attached file. a. Use Excel to obtain a simple sample of size 15 from this frame. b. Using the sample generated in part a, construct a 99% confidence interval for the mean average annual household income

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

Hypothesis Test: Example Problem

A survey of an urban university (population 25,450) showed that 870 of 1100 students sampled supported a fee increase to fund improvements to the student recreation center. Using the 95% level of confidence, what is the confidence interval for the true proportion who support the fee increase?

Statistics - Confidence Interval for μ

Find a confidence interval for μ assuming that each sample is from a normal population. a. ¯x = 14, σ = 4, n = 5, 90 percent confidence b. ¯x = 37, σ = 5, n = 15, 99 percent confidence c. ¯x = 121, σ = 15, n = 25, 95 percent confidence

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 for standard hemoglobin readings

The standard hemoglobin reading for healthy adult men is 15g/100ml with a standard deviation of 2g. For a group of 25 men we find a mean hemoglobin of 16.0g. Obtain a 95% confidence interval and give its interpretation.

Confidence Interval - In 1992, the FAA conducted 86,991 pre-employment drug tests on job applicants who were to be engaged in safety and security-related jobs, and found that 1,143 were positive. ...

In 1992, the FAA conducted 86,991 pre-employment drug tests on job applicants who were to be engaged in safety and security-related jobs, and found that 1,143 were positive. (a) Construct a 95 percent confidence interval for the population proportion of positive drug tests. (b) Why is the normality assumption not a problem

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

95% Confidence interval for mail ad preferences

A survey showed that out of 200 adults 51% of adults prefer to receive advertisement through the mail. Construct a 95 % confidence interval for the proportion of adults who prefer to receive ads through the mail.

Chebyshev Theorem and Confidence Interval

1. a) Use Chebyshev's theorem to find what percent of the values will fall between 120 and 150 for a data set with mean of 135 and standard deviation of 7.5 b) Use the Empirical Rule to find what two values 95% of the data will fall between for a data set with mean 234 and standard deviation of 12 2. An aptitude test ha

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 Intervals - Lunches

In a certain countrywide school district, a survey of 350 students showed that 28% carried their lunches to school. Find the 95% confidence interval of the true proportion of students who carried their lunches to school. If the cafeteria manager wanted to be reasonably sure that all the children who didn't bring their lunches co

Confidence Intervals and Sample Size Determination

A recent study indicated that 29% of the 100 women over age 55 in the study were widows. a. How large a sample must one take to be 90% confident that the estimate is within 0.05 of the true proportion of women over ages 55 who are widows? b. If no estimate of the sample proportion is available how large should the sample

Confidence Interval - Sample of VCR Owners

NBC asked a sample of VCR owners to record "Late Night with David Letterman" on their VCRs. Of the 125 VCR owners surveyed, 83 either "gave up or screwed up" because they did not understand how to program the VCR. (a) Construct a 90 percent confidence interval for the true proportion of VCR owners who cannot program their VCRs.

Confidence Interval

Dr. Patton is a Professor of English. Recently he counted the number of misspelled words in a group of student essays. For his class of 40 students, the mean number of misspelled words was 6.05 and the standard deviation 2.44 per essay. Construct a 95 percent confidence interval for the mean number of misspelled words in the pop

Confidence interval for the population mean: Use of the t distribution

A toy manufacturer wants to see how long, on average, a new toy captures children's attention. He tests 14 children selected at random and finds that their mean attention span is 23 minutes with a standard deviation of 7 minutes. If we assume that attention spans are normally distributed, find a 99% confidence interval for the m

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