Exam 7: Sampling and Sampling Distributions

Random samples of size 81 are taken from an infinite population whose mean and standard deviation are 200 and 18, respectively. The distribution of the population is unknown. The mean and the standard error of the mean are

A population of 1,000 students spends an average of $10.50 a day on dinner. The standard deviation of the expenditure is $3. A simple random sample of 64 students is taken. a.What are the expected value, standard deviation, and shape of the sampling distribution of the sample mean? b.What is the probability that these 64 students will spend a combined total of more than $715.21? c.What is the probability that these 64 students will spend a combined total between $703.59 and $728.45?

The following information was collected from a simple random sample of a population. The point estimate of the population standard deviation is

The following data was collected from a simple random sample of a population. The point estimate of the population mean

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

For a population with any distribution, the form of the sampling distribution of the sample mean is

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.

How many different samples of size 3 can be taken from a finite population of size 10?

Cluster sampling is

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.

Random samples of size 49 are taken from a population that has 200 elements, a mean of 180, and a variance of 196. The distribution of the population is unknown. The mean and the standard error of the mean are

A random sample of 15 telephone calls in an office showed the duration of each call and whether it was a local or a long distance call. a.What is the point estimate for the average duration of all calls? b.What is the point estimate for the standard deviation of the population? c.What is the point estimate for the proportion of all calls that were long distance?

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

The standard deviation of a sample of 100 elements taken from a very large population is determined to be 60. The variance of the population

As a rule of thumb, the sampling distribution of the sample proportions can be approximated by a normal probability distribution whenever

A population consists of 500 elements. We want to draw a simple random sample of 50 elements from this population. On the first selection, the probability of an element being selected is

A population has a mean of 75 and a standard deviation of 8. A random sample of 800 is selected. The expected value of is

Parameters are

An automotive repair shop has determined that the average service time on an automobile is 130 minutes with a standard deviation of 26 minutes. A random sample of 40 automotive services is selected. a.Compute the standard error of the mean. b.What is the probability that the sample of 40 automotive services will have a mean service time greater than 136 minutes? c.Assume the population consists of 400 automotive services. Determine the standard error of the mean.

The number of different simple random samples of size 5 that can be selected from a population of size 8 is