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Confidence Interval

Statistics for Managers: Confidence interval estimate problems

1. If X=85 (sample mean), 8 is population standard deviation, and n=64 is sample size, construct a confidence interval estimate for the population mean. 2. The manager of a paint supply store wants to estimate the actual amount of paint contained in 1-gallon cans purchased from a nationally known manufacturer. The manufactue

Statistics: Coefficient and Confidence interval - mean

See attached file for 3 problems: time for Speedy-Lub oil change, Google manager's salaries, Accu-Copiers' service times 2. The length of time to do a complete full service oil change at Speedy-Lube is normally distributed with a mean of 15.8 minutes and a standard deviation of 2.2 minutes X P(X < x) P(X > x) Mean Std dev 1

Comparing Hospital Charges

See attached file. Using the spreadsheet attached (and please send the completed document back), please use MegaStat to answer the following questions: 1. Do charges incurred by a patient depend on the type of insurance the patient has? If so, how? This is a hypothesis test where we could examine the average charges for pa

Statistics: Difference in mean total cholesterol levels between treatments

8. The following data were collected in a clinical trial to compare a new drug to a placebo for its effectiveness in lowering total serum cholesterol. Generate a 95% confidence interval for the difference in mean total cholesterol levels between treatments. New Drug (n=75), Mean (SD) Total Serum Cholesterol = 185.0

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5. A study is run comparing HDL cholesterol levels between men who exercise regularly and those who do not. The data are shown below. Regular Exercise = Yes, N = 35,Mean = 48.5, Std Dev = 12.5 Regular Exercise = No, N =120, Mean = 56.9 ,Std Dev = 11.9 Generate a 95% confidence interval for the differenc

Confidence Interval & Sample size: Body Mass Index

1. The following are body mass index (BMI) scores measured in 12 patients who are free of diabetes and participating in a study of risk factors for obesity. Body mass index is measured as the ratio of weight in kilograms to height in meters squared. Generate a 95% confidence interval estimate of the true BMI. 25, 27, 31 ,33

Random sample of 40 members of YMCA of South Jersey

See Attachment. Marty Rowatti recently assumed the position of director of the YMCA of South Jersey. He would like some current data on how long current members of the YMCA have been members. To investigate, suppose he selects a random sample of 40 current members. The mean length of membership of those in

Statistics: Confidence interval for population mean; estimate value of the mean

Questions A sample of 81 observations is taken from a normal population with a standard deviation of 5. The sample mean is 40. Determine the 95% confidence interval for the population mean. ____________ Dr. Patton is a professor of English. Recently she counted the number of misspelled words in a group of student essays

Statistics: Solve the Limits of the Confidence Interval

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 10 children selected at random and finds that their mean attention span is 33 minutes with a standard deviation of 6 minutes. If we assume that attenti

Hypothesis Testing & Confidence Interval: Population Mean

Average cost of $3,200 for products. n=25. After review it seems mean cost is $2,000 with a standard deviation of $150. Test that average cost is $3,200 or more versus $2,000. assume level of significance of .05. What is the null hypothesis and the alternative hypothesis? What is the critical value and the p-value? What is

Confidence Interval

Compute the 99% confidence interval based on four data points that have a sample mean of 71.5 and a sample standard deviation of 16.6032

Ranking Factors

Ranking Factors. In a nationwide survey of 1000 companies with more than 50 employees, managers were asked to rank various factors that influence their decisions in hiring employees. Each factor was ranked on a scale of 1 to 10, with 1 being not important and 10 being very important. The factor "educational background" re

Statistics: Should Tesla Motors buy axles from Crhis Cross Manufacturing

Tesla Motors needs to buy axles for their new car. They are considering using Chris Cross Manufacturing as a vendor. Tesla's requirement is that 95% of the axles are 100 cm ± 2 cm. The following data is MegaStat output from a test run from Chris Cross Manufacturing. Should Tesla select them as a vendor? Explain your answer.

Confidence Interval: Mean Salary of Google Managers

A random sample a 16 Google managers yield the following information on annual salaries. The sample mean is $69,000, with a sample standard deviation of $4,000. What is the mean salary of all Google managers? What is the 95% confidence interval for the population mean? Confidence interval - mean 95%

Confidence Interval and Sample Size

1. A consumer group would like to estimate the average amount of P G and E bill for the month of March for single family homes in the San Francisco Bay area. Based on studies conducted in other similar climate cities, the standard deviation is assumed to be $25. The group would like to estimate the average March bill to be withi

Statistics: Problems and Solutions

1. A sample of 35 golfers showed that their average score on a particular golf course was 80 with a standard deviation of 6. Answer each of the following (show all work): (A) Find the 95% confidence interval of the mean score for all 35 golfers. (B) Find the 95% confidence interval of the mean score for all golfers if this

Statistics: confidence interval, Margin of error, Sample mean, Population variance

1. A researcher wishes to estimate with 99% Confidence, the proportion of adults who have high-speed internet access. Her estimate must be accurate within 5% of the true Proportion. (a) Find the minimum sample needed, using a prior study that found that 54% of the respondents said they have high-speed internet access. (b) No p

Statistics: mean repair cost for washing machine; 10 bottles of cough syrup


Confidence interval: Take-out dinner, Grand Strand Medical, real estate, TV news

27. A recent study focused on the number of times men and women who live alone buy take-out dinner in a month. The information is summarized below. At the .01 significance level, is there a difference in the mean number of times men and women order take-out dinners in a month? What is the p-value? Statistic Men Women S

Effect on costs for reduced length of patient hospital stay

Your hospital is negotiating with medical insurance providers, who would like to reduce the amount they pay as reimbursement for hospital stays. For a particular procedure, they would like to reduce payment by $300 and have patients go home one day earlier. To see what effect this would have one hospital costs, a random samp

Confidence intervals, null hypothesis for population mean weight loss

Attached is the data needed. 1. Test the null hypothesis that the population mean weight loss is zero versus the alternative hypothesis that the mean weight loss is greater than zero. use .05 and assume the population of weight loss is normally distributed. Also compute the p value. 2. What values of the sample mean we