Exam 7: Sampling and Sampling Distributions

A department store has determined that 25% of all their sales are credit sales. A random sample of 75 sales is selected. a What is the probability that the sample proportion will be greater than 0.34? b.What is the probability that the sample proportion will be between 0.196 and 0.354? c.What is the probability that the sample proportion will be less than 0.25? d.What is the probability that the sample proportion will be less than 0.10?

An automotive repair shop has determined that the average service time on an automobile is 2 hours with a standard deviation of 32 minutes. A random sample of 64 services is selected. a.What is the probability that the sample of 64 will have a mean service time greater than 114 minutes? b.Assume the population consists of 400 services. Determine the standard error of the mean.

Exhibit 7-2 Four hundred registered voters were randomly selected asked whether gun laws should be changed. Three hundred said "yes," and one hundred said "no." -Refer to Exhibit 7-2. The point estimate of the proportion in the population who will respond "no" is

A sample statistic, such as , that estimates the value of the corresponding population parameter is known as a

A finite population correction factor is needed in computing the standard deviation of the sampling distribution of sample means

A sample of 92 observations is taken from a process (an infinite population). The sampling distribution of is approximately normal because

There are 8,000 students at the University of Tennessee at Chattanooga. The average age of all the students is 24 years with a standard deviation of 9 years. A random sample of 36 students is selected. a.Determine the standard error of the mean. b.What is the probability that the sample mean will be larger than 19.5? c.What is the probability that the sample mean will be between 25.5 and 27 years?

The average weekly earnings of bus drivers in a city are $950 (that is ) with a standard deviation of $45 (that is ). Assume that we select a random sample of 81 bus drivers. a.Assume the number of bus drivers in the city is large compared to the sample size. 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?

Convenience sampling is an example of

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 sample of 51 observations will be taken from a process (an infinite population). The population proportion equals 0.85. The probability that the sample proportion will be between 0.9115 and 0.946 is

A probability sampling method in which we randomly select one of the first k elements and then select every kth element thereafter is

The value of the ___________ is used to estimate the value of the population parameter.

The standard error of the proportion will become larger as

A population has a mean of 84 and a standard deviation of 12. A sample of 36 observations will be taken. The probability that the sample mean will be between 80.54 and 88.9 is

A sample of 24 observations is taken from a population that has 150 elements. The sampling distribution of is

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 consists of 8 items. The number of different simple random samples of size 3 (without replacement) that can be selected from this population is

Exhibit 7-2 Four hundred registered voters were randomly selected asked whether gun laws should be changed. Three hundred said "yes," and one hundred said "no." -Refer to Exhibit 7-2. The point estimate of the proportion in the population who will respond "yes" is

In a restaurant, the proportion of people who order coffee with their dinner is 0.9. A simple random sample of 144 patrons of the restaurant is taken. a.What are the expected value, standard deviation, and shape of the sampling distribution of ? b.What is the random variable in this problem? Define it in words. c.What is the probability that the proportion of people who will order coffee with their meal is between 0.85 and 0.875? d.What is the probability that the proportion of people who will order coffee with their meal is at least 0.945?