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# Confidence Interval

### Find a 98% confidence interval for the true mean heart rate of all people with the untreated condition. Interpret this confidence interval and write a sentence that explains it.

A drug manufacturer wants to estimate the mean heart rate for patients with a certain heart condition. Because the condition is rare, the manufacturer can only find 29 people with the condition currently untreated. From this small sample, the mean heart rate is 90 beats per minute with a standard deviation of 5. (a) Find a 98

### Statistics:

See attached file. Pg 2-2 A GE flourescent bulb's useful life is normally distrbuted. We wish to estimate the mean lifetime. A random sample of 15 bulbs are: 2,222 hrs standard deviation of 310 hrs Refer to table 7A a) Determine 95% confidence interval b) If an executive can say the the average expected life

### Statistics: Market share for a radio station

See attached file. PG 2-1 You are in charge of selling advertising for a radio station. The fees are directly related to the share of the listening market. When 200 listeners were contacted randomly, 25 respondents said they listened to the station. Refer to Table 6C attached. A) What is the 95% confidence interval

### A sample from a 1,591-page phone directory; unpopped kernels of popcorn

1) 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: 0 260 356

### Extra Credit work

Number 1 The union for a particular industry has determined that the standard deviation of the daily wages Find a 90% confidence interval for the true mean daily wage of all union workers in the industry. Then complete the table below. Carry your intermediate computations to at least three decimal places. Round your answers

### Construct 95% Confidence Interval

The National Student Loan Survey collects data to examine questions related to the amount of money that borrowers owe. The survey selected a sample of 1280 borrowers who began repayment on their loans between 4 and 6 months prior to the survey. The mean debt for undergraduate study was \$18,900 and the standard deviation was abou

### Confidence interval: Use of Blackberries by students at OSU

Suppose you have drawn a simple random sample of 225 students from OSU. In this sample, 45 students own Blackberries. Let &#960; denote the proportion of OSU students who own Blackberries. Construct a 95% confidence interval for &#960;. Suppose you have drawn a simple random sample of 100 students from OSU and recorded

### Daniel-James Financial Services: Confidence interval and prediction interval

Please show all the work. 1. 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

### Margin of error for cost of wedding

Bride's magazine reported that the mean cost of a wedding is \$25,000. Assume that the population standard deviation is \$8400. Bride's plans to use an annual survey to monitor the cost of a wedding. Use 99% confidence. What is the recommended sample size if the desired margin of error is \$651?

### Calculations of Margin of Error

A national Retail Foundation survey found housholds intended to spend an average of \$932 during the December holiday season. Assume that the survey included 850 households and that the standard deviation of the sample is \$215. A With 95% confidence, what is the margin of error?

### Variance, estimator for mean, millionaire net worth

#1 Suppose you are sampling from a population with mean µ = 1,065 and standard deviation &#963; = 500. The sample size is n = 100. What are the expected value and the variance of the sample mean X? Show and explain your work (study guide # 5-41). #2 Suppose a new estimator for the population mean is discovered. The new

### Statistics-confidence intervale

1. Given the values of x calculate the standard error of the mean 13 12 9 15 11 16 17 8 12 7 12 2. Given the above numbers calculate the standard error of the mean 3.Given the following data, construct a 95% confidence intervale _ Statistic X S n a Value 113 15 9 .05 4. Constru

### Confidence Intervals

Please help me create and interpret the confidence intervals- 90%, 95%, and 99%.. 1)Compute the confidence interval(s) for the attached data (data and graphs)Distance only. 2)Provide graph and table in excel 3)Based on the confidence interval(s), determine if you would change the conclusion that distance does affect a home

### Point Estimates & Confidence Interval

A simple random sample of 8 employees is selected from a large firm. For the 8 employees, the number of days each was absent during the past month was found to be 1, 3, 3, 3, 1, 5, 4, and 3 (a) What is the point estimate for , the mean number of days absent for the firm's employees? Round your answer to nearest hundredth. =

### Confidence interval

A human resource manager for Carver County is evaluating a recent effort to improve the health of the county's firefighters by providing an exercise room in each of the county's firehouses. Their records prior to installing the exercise rooms indicate that the mean weight of all county firefighters is 198 pounds with a standard

### General Statistics

1. Suppose a wildlife service wishes to estimate, with 99% confidence, the mean number of days of hunting per hunter for all licensed hunters in the state during a given season, with a bound on the error of estimation equal to 2 hunting days. How many hunters must be included in the survey? Assume that the data collected in earl

### Hypothesis Testing and Confidence Interval Problem

A. *HT* A test was conducted to compare the wearing quality of the tires produced by two tire companies. A random sample of 16 cars is equipped with one tire of Brand X and one tire of Brand Y (the other two tires on each car are not part of the test), and driven for 30 days. The following table gives the amount of wear in thous

### Statistcs: Phone Directory and Popcorn Kernels Statistics

Question 1: 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:

### Standardized test of manual dexterity

You have administered a standardized test of manual dexterity to two groups of 10 semi skilled workers. One of these two groups of workers will be employed by you to work in a warehouse with many fragile items. The higher the manual dexterity of a worker the less likelihood that worker will break significant inventory. Because o

### Standard Deviation

The lifetime of a certain brand of battery is known to have a standard deviation of 11.5 hours. Suppose that a random sample of 50 such batteries has a mean lifetime of 34.5 hours. Based on this sample, find a 90% confidence interval for the true mean lifetime of all batteries of this brand.

### Confidence Interval

(1) The lifetime of a certain brand of battery is known to have a standard deviation of 19.8 hours. Suppose that a random sample of 50 such batteries has a mean lifetime of 40.9 hours. Based on this sample, find a 95% confidence interval for the true mean lifetime of all batteries of this brand. Then complete the table below.

A recent survey of 50 executives who were laid off from their previous position revealed it took a mean of 26 weeks for them to find another position. The standard deviation of the sample was 6.2 weeks. Construct a 95 percent confidence interval for the population mean. Is it reasonable that the population mean is 28 weeks? Just

### Applied Business Statistics: Sampling error, state meat inspector, applicant drug test

21. What is sampling error? Could the value of the sampling error be zero? If it were zero, what would this mean? 22. List the reasons for sampling. Give an example of each reason for sampling. 32. A state meat inspector in Iowa has been given the assignment of estimating the mean net weight of packages of ground chuck la

### Confidence Interval and Sample Size: Ameritech Phone Directory

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: 0 260 356

### Statistics: Set of five questions

See attached file for 5 questions: Mean weight of carry-on luggage Mean of a population Lifetimes of washing machines Proportion of Democrats in sample of registered voters Proportion of customers who use stor credit card for purchases In order to determine the average weight of carry-on luggage by passengers in airpla

### Statistics Problems

1. Find the indicated critical z value. Find the value of z&#945;/2 that corresponds to a confidence level of 97.80%. 2. Find the appropriate minimum sample size. You want to be 95% confident that the sample variance is within 20% of the population variance. 4. Express the confidence interval using the indica

### 4 Statistics Problems: types of data, parameter, sample mean, confidence intervals

1: Which type of data (nominal, ordinal, interval, ratio) is each of the following variables? Explain. a. Number of employees in the Wal-Mart store in Hutchinson, Kansas. b. Number of merchandise returns on a randomly chosen Monday at a Wal-Mart store. c. Temperature (in Fahrenheit) in the ice-cream freezer at a Wal-Mart stor

### Confidence level for variance

You randomly select and measure the contents of 10 bottles of cough syrup. The results (in fluid ounces are shown. 4.216 4.292 4.252 4.244 4.186 4.281 4.269 4.243 4.222 4.231 Assume the sample is taken from a normally distributed population. Construct 98% confidence intervals for (a) &#963;2 the population

### Confidence Interval for Mean Blood Pressure

A researcher wishes to determine whether people with high blood pressure can reduce their blood pressure by following a particular diet. Use the sample data below to test the claim that the treatment population mean mu_1 is smaller than the control population mean mu_2. Test the claim using a significance level of 0.01. You m

### Statistics Module: Correlation and Regression

Module 6: Correlation and Regression A For the supermodel dataset at the right, treat height as the explanatory variable and weight as the response variable. (Data set is given in the excel file) 1 Is there a significant correlation? Show the null hypothesis, df and the test you used. yes/