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    Confidence Interval

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    What is the 95% confidence interval estimate of u?

    1) Suppose that 64 smokers were sampled. Assume the sample mean and the sample standard deviation remained the same ($20 and $5, respectively). a. What is the 95% confidence interval estimate of u? b. A research a firm a conducted a survey to det

    Sample Size in Validity Studies

    I am struggling with this portion of my assignment, please provide guidance. Using the attached article, provide an overview of the contents and apply the concepts to the Job Satisfaction survey. It is important to cover the concept of the techniques used to estimate sample size. See attachments.

    Confidence interval problem

    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

    The American Sugar Producers Association

    12. The American Sugar Producers Association wants to estimate the mean yearly sugar consumption. A sample of 16 people reveals the mean yearly consumption to be 60 pounds with a standard deviation of 20 pounds. a. What is the value of the population mean? What is the best estimate of this value? b. Explain why we need to u

    Suppose that 64 smokers were sampled...

    Suppose that 64 smokers were sampled. Assume the sample mean $20 and the sample standard deviation $5. a. What is the 95 percent confidence interval estimate of _? b. Explain why this confidence interval is narrower than the one determined in the previous exercise.

    What is the confidence interval for the mean number of misspelled words?

    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

    The real estate data is now in an excel spreadsheet

    UPDATE - Part B is the most important - if you are only able to help with that part, please do so. Refer to the Real Estate data, which reports information on homes sold in Denver, Colorado,last year. a. Let selling price be the dependent variable and size of the home the independent variable. Determine the regression e

    Confidence interval for ratio of 2 population variances

    A manufacturer needs to compare the weights of a product produced at 2 different plants. A random sample of 16 items from Plant A has a standard deviation of 12 milligrams and a random sample of 25 items from Plant B has a standard deviation of 15 milligrams. Assuming that both populations are normally distributed, construct a

    Confidence Interval for the Population Variance

    A discount store is trying to decide whether to use a single waiting line for available cashiers. The waiting times for 25 randomly selected customers was found to have a standard deviation of 1.7 minutes. Construct a 95% confidence interval for the population variance. What assumptions must be made to construct a valid confid

    Point Estimation and Confindence Intervals of Quartiles

    The following data are the lifetimes (in hours) of 20 certain electrical components: 6278 3113 9350 5236 11584 12628 7725 8604 14266 6215 3212 9003 3523 12888 9460 13431 17809 2812 11825 2398 Find a point estimate and 90% confidence interval for the population lower quartile. Can you explain how and why we do the follo

    Means and Confidence Levels

    Dr. Walker is an industrial psychologist. She is currently studying stress among executives of Internet companies. She has developed a questionnaire that she believes measures stress. A score above 80 indicates stress at a dangerous level. A random sample of 15 executives revealed the following stress level scores. 94 78

    Mean, variance, confidence interval

    1. Compute the mean and variance of the following discrete probability distribution. x P(x ) 0 .20 1 .40 2 .30 3 .10 2. In a binomial situation n = 4 and π = .25. Determine the probabilities of the followi

    Confidence Interval

    Dunkin Donuts advertises that a dozen of their donuts weighs about 43 oz. A certain baker has figured out that she can stay out of trouble with her manager if each donut weighs about 3.6 oz. To test her donut-making process, she randomly selects thirty-one donuts after baking and weighs them. The average of the sample is 3.50

    Confidence Interval Estimation, Mean and Standard Deviation

    Confidence Interval Estimation 1. Compute a 95% confidence interval for the population mean, based on the sample 1, 2, 3, 4, 5, 6, and 30. Change the number from 30 to 10 and recalculate the confidence interval. Using the results, describe the effect of an outlier or extreme value on the confidence interval. 7.285714 mean 1

    Normal Distribution: proportion, probability, confidence interval, sample size,

    1. Suppose that the mean income of all Mudville residents is $40,000 with a standard deviation of $6,000. Answer the following questions in terms of these data. a. What proportion of all possible samples of 36 Mudville residents would have a mean income of $38,000 or more? b. What is the probability of selecting a rando

    Inverse Demand Relation Problem

    An Econometrician has estimated the inverse demand relation as: P = a + b Q + e and found that a = 400, b = -2.75, e (a) = 8, e (b) = 0.75. Find the approximmate 95% confidence interval for the true values of a and b.

    Confidence Interval

    Calculate a 95% confidence interval of the average number of Orlando Dining magazines sold over the last year. The average number sold per month is 11,500 and the standard deviation is 575.

    Confidence interval and test of hypothesis

    Please help with the following problems. The manager of a local bank wants to estimate the average amount held in checking accounts by the customers. A random sample of 30 customers is selected, and the results indicate a sample average of $4,750 and a sample standard deviation of $1,200. a) Set a 95% confidence interval

    Confidence intervals

    The inspection division of the Measures Department in a public service is interested in estimating the actual amount of soft drink that is placed in 2 -liter bottles at the local bottling plant of a large nationally known soft-drink company. The bottling plant has informed the inspection division that the standard deviation for

    Normal Distribution: 68-95-99.7 Rule, Confidence Interval

    1. The Environmental Protection Agency (EPA) fuel economy estimates for automobiles tested recently predicted a mean of 24.8 mpg with a standard deviation of 6.2 mpg for highway driving. Assume that the data is normally distributed. Using the 68-95-99.7 Rule, Determine: a. Within what interval you would expect the middle

    Statistics: Standard Error and Sampling Size

    Mr. James McWhinney, president of Daniel-James Financial Services, believes there is a relationship between the number of client contacts and the dollar amount of sales. To document this assertion, Mr. McWhinney gathered the following sample information. The X column indicates the number of client contacts last month, and the Y

    Questions about Z score, confidence intervals, probabilities

    Distribution and probability questions (See attached file for full problem description) --- 1. A normal distribution has a mean of 50 and a standard deviation of 4. a. Compute the probability of a value between 44.0 and 55.0. b. Compute the probability of a value greater than 55.0. c. Compute the probability of a valu

    Two statistics questions on Hypergeometric Distribution and Confidence intervals

    71. Refer to the Baseball 2000 data (Appendix K), which contains information on the 2000 Major League Baseball season. There are 30 teams in the major leagues, and 7 of them have home fields with artificial playing surfaces. As part of the negotiations with the players' union, a study regarding injuries on grass versus artificia

    Estimation and Confidence Intervals

    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% confidence interval for the mean number of misspelled words in the popul

    Confidence Interval and Sampling Error

    ComputerWare asked 500 of its iMac purchasers what computer they owned or had owned. There were 83 new computer owners, 60 who had owned a Windows-based computer, and 357 who had owned a Macintosh. The proportion of first-time computer owners was 83/500 = 0.167. So, 0.167 is an estimate of the proportion of new computer owners.

    Statistics

    Need help with chapter review questions attached.

    Statistics - data

    Case study problem attached. --- The following are the number of chips per bag for the 42 bags of Chips Ahoy! analyzed. 1200 1219 1103 1213 1258 1325 1295 1247 1098 1185 1087 1377 1363 1121 1279 1269 1199 1244 1294 1356 1137 1545 1135 1143 1215 1402 1419 1166 1132 1514 1270 1345 1214 1154 1307 1293 1546 1228 1239 14