Exam 7: Sampling and Sampling Distributions

The milk prices (in quarts)from a sample of 9 convenience stores in Chattanooga,Tennessee are shown below. a.What is the point estimate for the prices of all convenience stores in Chattanooga? b.What is the point estimate for the standard deviation of the population?

The number of random samples (without replacement)of size 3 that can be drawn from a population of size 5 is

There are 500 employees in a firm,45% are female.A sample of 60 employees is selected randomly. a.Determine the standard error of the proportion. b.What is the probability that the sample proportion (proportion of females)is between 0.40 and 0.55?

A simple random sample of 6 computer programmers in Houston,Texas revealed the sex of the programmers and the following information about their weekly incomes. a.What is the point estimate for the average weekly income of all the computer programmers in Houston? b.What is the point estimate for the standard deviation of the population? c.Determine a point estimate for the proportion of all programmers in Houston who are female.

The following information gives the number of days absent from work for a population of 5 workers at a small factory. a.Find the mean and the standard deviation for the population. b.Samples of size 2 will be drawn from the population.Use the answers in part a to calculate the expected value and the standard deviation of the sampling distribution of the sample mean. c. c.Find all the samples of 2 workers that can be extracted from this population.Choose the samples without replacement. d.Compute the sample mean $\bar{x}$ for each of the samples in Part

The average weekly earnings of bus drivers in a city are $950 (that is $\mu$ )with a standard deviation of $45 (that is $\sigma$ ).Assume that we select a random sample of 81 bus drivers. a.Compute the standard error of the mean. b.What is the probability that the sample mean will be greater than $960? c.If the population of bus drivers consisted of 400 drivers,what would be the standard error of the mean?

Cluster sampling is

A bank has kept records of the checking balances of its customers and determined that the average daily balance of its customers is $300 with a standard deviation of $48.A random sample of 144 checking accounts is selected. a.What is the probability that the sample mean will be more than $306.60? b.What is the probability that the sample mean will be less than $308? c.What is the probability that the sample mean will be between $302 and $308? d.What is the probability that the sample mean will be at least $296?

A simple random sample of 6 recent graduates revealed the following information about their weekly incomes. a.What is the expected value of the average weekly income of all the recent graduates? b.What is the expected value of the standard deviation for the population?

As the sample size increases,the variability among the sample means

MNM Corporation gives each of its employees an aptitude test.The scores on the test are normally distributed with a mean of 75 and a standard deviation of 15.A simple random sample of 25 is taken from a population of 500. a.What are the expected value,the standard deviation,and the shape of the sampling distribution of $\bar{x}$ ? b.What is the probability that the average aptitude test in the sample will be between 70.14 and 82.14? c.What is the probability that the average aptitude test in the sample will be greater than 82.68? d.What is the probability that the average aptitude test in the sample will be less than 78.69? e.Find a value,C,such that P( $\bar{x}$ $\ge$ C)= .015.

Starting salaries of a sample of five management majors along with their genders are shown below. a.What is the point estimate for the starting salaries of all management majors? b.Determine the point estimate for the variance of the population. c.Determine the point estimate for the proportion of male employees.

A population has a standard deviation of 16.If a sample of size 64 is selected from this population,what is the probability that the sample mean will be within 2 of the population mean?

The sample statistic s is the point estimator of

Random samples of size 36 are taken from an infinite population whose mean and standard deviation are 20 and 15,respectively.The distribution of the population is unknown.The mean and the standard error of the mean are

Exhibit 7-3 In a local university,40% of the students live in the dormitories.A random sample of 80 students is selected for a particular study. -Refer to Exhibit 7-3.The probability that the sample proportion (the proportion living in the dormitories)is at least 0.30 is

Random samples of size 525 are taken from an infinite population whose population proportion is 0.3.The standard deviation of the sample proportions (i.e. ,the standard error of the proportion)is

Below you are given the values obtained from a random sample of 4 observations taken from an infinite population. a.Find a point estimate for $\mu$ .Is this an unbiased estimate of $\mu$ ? Explain. b.Find a point estimate for $\sigma$ ².Is this an unbiased estimate of $\sigma$ ²? Explain. c.Find a point estimate for $\sigma$ . d.What can be said about the sampling distribution of $\bar{x}$ ? Be sure to discuss the expected value,the standard deviation,and the shape of the sampling distribution of $\bar{x}$ .

The probability distribution of the sample mean is called the

A simple random sample of 64 observations was taken from a large population.The sample mean and the standard deviation were determined to be 320 and 120 respectively.The standard error of the mean is