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Confidence Interval

Construct the 99% confidence interval

4400 students surveyed about length of time to complete bachelor's. The mean is 5.15 years and the standard deviant is 1.68 years. Based on these sample data, construct the 99% confidence interval for the mean time required by all students.

3758-stats

Details: The estimated value of a population mean is $120, and the upper limit of the 90% confidence interval is $140. A 95% confidence interval has also been constructed. Given this information, which of the following best describes the lower limit of the 95% confidence interval?

Statistics - confidence intervals

The average weekly earnings for women in managerial and professional positions is $685 with a standard deviation of $45. Salaries are normally distributed. Answer the following questions. a. What is the probability that a woman will have a weekly salary of more than $650? b. What is the probability that a woman will hav

Confidence interval, error of estimate, sample size

In the publication Employment and Earnings, information on the ages of people in the civilian labor force was published. Seventy-five people in the civilian labor force are randomly selected. The mean age is 37.4 years with a standard deviation of 10.3 years. a. Find the 99% confidence interval for the mean age. b. W

Use given degree of confidence and sample data

Use given degree of confidence and sample data to find a) margin of error E and b) the confidence interval for the population mean mu. Starting salaries of college graduates who have taken a statistics course: 95% confidence; n=100, mean of the values in a sample (x with line above)= $43,704, s= $9879.

Refer to the OECD data, which reports information on census, economic, and business data for 29 countries. a. Develop a 90 percent confidence interval for the mean percent of the population over 65 years. b. Develop a 90 percent confidence interval for the mean energy use.

Details: Refer to the OECD data, which reports information on census, economic, and business data for 29 countries. a. Develop a 90 percent confidence interval for the mean percent of the population over 65 years. b. Develop a 90 percent confidence interval for the mean energy use.

What is the lower/upper limit of the 99% confidence interval?

To estimate the percentage of a species of rodent that carries a specific viral infection, 150 rodents are randomly selected and examined, and 76 of them are found to be infected. Based upon this, find a 99% confidence interval for the proportion of all rodents of this species that are infected with the virus. Then complete the

Standard deviation, confidence interval

1. When the level of confidence and sample standard deviation remain the same, a confidence interval for a population mean based on a sample of n=100 will be ______ a confidence interval for a population mean based on a sample of n=50 a) wider than b) Narrower than c) equal to Explain answer: 2). If the box wei

Confidence interval for population variance

A random sample of size 9 of a random variable X gave a variance of 3.0. Find a 95% confidence interval for the population variance, assuming that X is normally distributed.

A confidence interval of the mean is determined.

This problem is solved: Let's summarize the method for finding the 95% confidence interval using a step-by-step illustration. Suppose that a certain automobile company wishes to determine the expected miles per gallon for one of its new models. Based on years of experience with cars, the company statistician realizes that not

The answer to 99% Confidence Interval

The standard deviation of the daily demand for a product is an important factor for inventory control for the product. Suppose that a pharmacy wants to estimate the standard deviation of the daily demand for a certain antibiotic. It is known that the daily demand for this antibiotic follows an approximately normal distribution.

In this problem, we have a population with a known standard deviation. We are given the sample mean from sample of size 31 and asked to find the 90% confidence interval for the mean of the underlying population.

A finance company needs to estimate the mean number of credit cards held by an American family. From past experience, the company knows that the standard deviation of the population is 1.16 cards. The company takes a random sample of n=31 families and finds the sample mean number of cards to be 4.6. Use this data to find a 90% c

Conference interval

A consulting firm which does consulting jobs on a cost per job basis wants to estimate its average pay per hour. The firm's manager takes a random sample of n=30 jobs and calculates the pay per an hour. The par per an hour values are listed below, rounded to the nearest dollar. 17 23 14 20 68 40 31 19 19 32 13 37 32 28 34 23 2

Confidence Interval for true mean

A savings and loan association needs information concerning the checking account balances of it's local customers. A random sample of 14 accounts was checked, yielding the following balances (rounded to the nearest dollar): 701 379 349 828 499 174 786 762 580 943 741 798 311 1096 Find a 99% confidence interval for the true me

Compute a 95% confidence interval for the standard deviation of the above data.

A financial analyst, known for her excellent track record, has decided to part company with her old partners and to enter the venture capital area. In it's publicity brochure, the firm she joins lists the market adjusted rate of return that their new partner achieved during her previous tenure. The table below shows these return

Estimation

In an election campaign, the party vying for an upset polls a sample of 100 voters. The party finds that 60 of 100 clearly express the intention of voting in favor of the party polling. How many voters should be sampled if the party wants to estimate the population proportion with a sampling error of 5% or less? (Use confide

Confidence interval for the difference of proportions

Please help with the following problem. Provide step by step calculations. After a certain candidate announced his intention for running for the premiership of a province, many polls were conducted to assess his chanced for success. Among them were two polls of independant samples taken from two populations. The poll in the

Confidence intervals and prediction intervals

Day 1 dose 123 Day 2 dose 139 Day 3 dose 85 Day 4 dose 133 Day 5 dose 91 Day 6 dose 110 Day 7 dose 118 What is the 95% one-sided confidence interval for the average worker? What is the 95% predicted dose for a 95% one-sided confidence interval?

A sample problem is solved.

Given the following information, calculate a confidence interval using a 95 percent confidence level: sample proportion =.4, standard error of the proportion =.05, and sample size =100.

Confidence intervals and hypothesis testing? Maybe?

A local merchant is interested in obtaining a small business loan to expand his business. He will be able to obtain a more favorable interest rate if he can reasonably demonstrate that his near-term monthly revenues will be between $10,000 and $15,000. He doesn't know the exact level of sales to expect over the next several mo

Confidence Intervals

A cutoff score of 79 has been established for a sample of scores in which the mean is 65. If the corresponding z-score is 1.4 and the scores are normally distributed, what is the standard deviation?

Confidence Interval

How do you figure a 90% confidence interval for the mean weight of all Siberian tigers in captivity from various zoo's, where the random sample is 31, the mean weight is 507 pounds from sample zoo's, with a standard deviation of 62 pounds?

Confidence Interval

Which of the following is not needed to be known to calculate a confidence interval? a. standard deviation b. sample size c. mean d. degree of confidence

Confidence Interval and Statistical Analysis

Find the confidence interval and conduct statistical analysis for the given problems. 6. A producer of a juice drink advertises that it contains 10% real fruit juices. A sample of 75 bottles of the drink is analyzed and the percent of real fruit juices is found to be 6.5%. If the true proportion is actually .10, what is th

Probability/Confidence Level

1) Megacorp wants to determine whether the mean of all one-day travel expenses in Moscow exceeds $500. A simple random sample of 35 one-day travel expenses is obtained from Megacorp travel expense files. The average one-day Moscow expense was found to be $538 with a standard deviation of $41. a) Calculate the probability of

Statistic problem

2 Questions: 3) Using the CIELO data, calculate 95% and 99% confidence intervals for the percentage intending to purchase the CIELO. (see attachment for full question) -------------------------------------------------- 3) Using the CIELO data, calculate 95% and 99% confidence intervals for the Percentage intending to purcha

Calculate 95% and 99% confidence intervals for the mean selling price of vehicles sold by Winter Pontiac. Test the hypothesis that the mean selling price of automobiles sold by Winter Pontiac is less than $25,000. Use alpha= .05

1)      Calculate 95% and 99% confidence intervals for the means selling price of Vehicles sold by Winter Pontiac. 2)      Test the hypothesis that the mean selling price of automobiles sold by Winter Pontiac is less than $25,000. Use alpha= .05 To solve the problem 1 and 2 below use the following table

Statistics - Confidence Interval

Please provide step by step instructions using actual numbers instead of formulas for solving the following 3 problems, thanks 3. Determine whether the average number of calories in a homemade cookie is more than a store-bought one. Estimate the difference in the mean calories between the two types using a 90% confidence int