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Confidence Interval

Statistical Methodologies are reinforced.

A random sample of 16 Google managers yields 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? One-Sample T N 16 Mean 69000 StDev 400 SE Mean 10

Statistics calculations for brown bullheads in Great Lakes

Review questions below and indicate which confidence interval statistic you would use in each case (z-sigma, Z-s, or t-s): Brown bullheads are a common Great lakes feeding fish and indicator species for sediment health. The current study focused on the weight of fish taken in various locations. a. A sample of 27 brown bull

Confidence interval for proportion of loan credit ratings

A bank's loan officer rates applicants for credit. The ratings are normally distributed with a mean of 200 and a standard deviation of 50. If 40 different applicants are randomly selected, find the probability that their mean is above 215. Construct a confidence interval for the population proportion p, given n = 182, x = 13

Evaluate: Confidence Interval for the Mean

In a poll of 200 randomly selected U.S. adults, 104 said they favored a new proposition. Based on this poll, compute a 99% confidence interval for the proportion of all U.S. adults in favor of the proposition (at the time of the poll). Then complete the table below. Carry your intermediate computations to at least three decim

Confidence Interval Application: Test medium sales prices

The US Census Bureau announce that the median sales price of new houses sold in April 2009 was $221,600 while the mean sales price was $274,300. Assume that the standard deviation of the prices is $90,000. a) If you select samples of n=2, describe the shape of the sample distribution of Xbar. b) If you select samples of

Construct Confidence Level of mobile home owners and their cell phone providers

A survey of 4,581 U.S. households that owned a mobile phone found that 58 percent are satisfied with the coverage of their cellular phone provider. Assuming that this was a random sample, construct a 90 percent confidence interval for the true proportion of satisfied U.S. mobile phone owners. (Round intermediate calculations


The U.S. Dairy Industry wants to estimate the mean yearly milk consumption. A sample of 16 people reveals the mean yearly consumption to be 60 gallons with a standard deviation of 20 gallons. a.) What is the value of the population mean? What is the best estimate of this value? b.) Explain why we need to use the t dist

Maximum Error of Estimate; Sample size; Confidence interval

Assume that a sample is drawn and z(±/2) = 1.96 and ? = 20. Answer the following questions: (A) If the Maximum Error of Estimate is 0.02 for this sample, what would be the sample size? (B) Given that the sample Size is 400 with this same z(?/2) and Ï?, what would be the Maximum Error of Estimate? (C) What happens

Confidence Intervals: Maximum error of estimation; sample size required

By measuring the amount of time it takes a component of a product to move from one workstation to the next, an engineer has estimated that the standard deviation is 3.93 seconds. Answer each of the following (show all work): (A) How many measurements should be made in order to be 99% certain that the maximum error of esti

Confidence Interval for Mean National Student Loan Survey

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

Case Study: Mean Overall Duration of Symptoms & Confidence Interval

Twenty-five volunteers who had developed cold symptoms within the last 24 hours were given zinc lozenges to take every 2 to 3 hours until their cold symptoms were gone. The mean overall duration of symptoms was 4.5 days with a standard deviation of 1.6 days. The selected cases have a distribution which appears to be symmetri

Stat Tutorials please

Q.8.1 Southside Hospital in Bay Shore, New York, commonly conducts stress tests to study the heart muscle after a person has a heart attack. Members of the diagnostic imaging department conducted a quality improvement project to try to reduce the turn-around time for stress tests. Turn around time is defined as the time from w

Statistical Process Control

Statistical Process Control: Control Limits and Confidence Intervals Calculate the statistical process control limits for the following data and explain the control limits and confidence intervals. [Please refer to the attachment for the data]

Families USA: Population mean yearly premium

Use MegaStat > Confidence Intervals Families USA, a monthly magazine that discusses issues related to health and health costs, surveyed 20 of its subscribers. It found that the annual health insurance premiums for a family with coverage through an employer averaged $10,979. The standard deviation of the sample was $1,000.

Sampling populations give 95% confidence intervals

Please give answers with steps. 1) The accounting firm of Ahmadi & Associates was commissioned to audit a population of 500 accounts. For this audit, Ahmadi & Associates selected a simple random sample of 64 accounts. The sample showed a mean discrepancy of $120 with a standard deviation of $24. Develop an approximate 95% co

Confidence Interval Calculations

1. Nancy Joon, Inc. has 1500 employees. A simple random sample of 81 employees was selected and the individuals I the sample were asked how much they contribute monthly to their retirement accounts. The mean amount for the sample was $150 with a standard deviation of $45. Develop an approximate 95% confidence interval for the me

Statisticss: Hospital is concerned about waiting times in emergency room

See attached data file. Problem Set: You work at a major regional hospital and you are concerned about waiting times in the emergency room. This file contains data on some random samples of patients. Use the data to answer the following questions. Problems 3.1 and 3.2 come from week 7 material, and 3.3 relates to week 8

Confidence Interval for Proportion

As a condition of employment, Fashion Industries applicants must pass a drug test. Of the last 220 applicants 14 failed the test. Develop a 99 percent confidence interval for the proportion of applicants that fail the test. Would it be reasonable to conclude that more than 10 percent of the applicants are now failing the test?

Analyze Unusual Baby Growth Patterns using Confidence Intervals

In order to identify baby growth patterns that are unusual, we need to construct a confidence interval estimate of the mean head circumference of all babies that are 2 months old. a random sample of 100 babies is obtained and the mean head circumferene is found to be 40.6cm. Assuming that the population standard deviation is kno

Fashion Industries random drug testing: step-by-step solution

As a condition of employment, Fashion Industries applicants must pass a drug test. Of the last 220 applicants 14 failed the test. Develop a 99 percent confidence interval for the proportion of applicants that fail the test. Would it be reasonable to conclude that more than 10 percent of the applicants are now failing the test? I

Determine population mean time for executives laid off to find another position

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

Standard curve questions are featured.

1. A man is in the process of buying a new car. He has a choice of 3 engine makes, 7 body styles and 10 colors. How many different cars does he have to choose from? 4. True or False? If false, correct it. For a given situation, the longer your confidence interval is, the lower your confidence in it is (why?).

Confidence Interval for Population Proportion..

Please solve the exercise below using Excel and show your work (with formulas). The production manager for the XYZ Manufacturing company is concerned that the customer orders are being shipped late. He asked one of his planners to check the timeliness of shipments for 1000 orders. The planner randomly selected 1000 orders and

Construct a 99 Percent Confidence Interval Around the Mean

A small town has a population of 20,000 people. Among these, 1,000 regularly visit a popular local bar. A sample of 100 people who visit the bar is surveyed for their annual expenditures in the bar. It is found that on average each person who regularly visits the bar spends about $2000 per year in the bar with a standard deviat

Hypothesis Tests & Confidence Intervals

In the 1980s, Tennessee conducted an experiment in which kindergarten students were randomly assigned to "regular" and "small" classes, and given standardized tests at the end of the year. ("Regular" classes contained approximately 24 students and "small" classes contained approximately 15 students.) Suppose that, in the popul