Exam 7: Sampling and Sampling Distributions

Suppose the ages of students in Statistics 101 follow a right skewed distribution with a mean of 23 years and a standard deviation of 3 years.If we randomly sampled 100 students,which of the following statements about the sampling distribution of the sample mean age is incorrect?

A manufacturer of power tools claims that the mean amount of time required to assemble their top-of-the-line table saw is 80 minutes with a standard deviation of 40 minutes.Suppose a random sample of 64 purchasers of this table saw is taken.The mean of the sampling distribution of the sample mean is ________ minutes.

The amount of bleach a machine pours into bottles has a mean of 36 oz.with a standard deviation of 0.15 oz.Suppose we take a random sample of 36 bottles filled by this machine.The sampling distribution of the sample mean has a mean of 36 oz.

For sample size 16,the sampling distribution of the mean will be approximately normally distributed

Why is the Central Limit Theorem so important to the study of sampling distributions?

A manufacturer of power tools claims that the mean amount of time required to assemble their top-of-the-line table saw is 80 minutes with a standard deviation of 40 minutes.Suppose a random sample of 64 purchasers of this table saw is taken.The standard deviation of the sampling distribution of the sample mean is ________ minutes.

To obtain a sample of 10 books in the store,the manager walked to the first shelf next to the cash register to pick the first 10 books on that shelf.This is an example of a

The professor of a business statistics class wanted to find out the mean amount of time per week her students spent studying for the class.Among the 50 students in her class,20% were freshmen,50% were sophomores and 30% were juniors.She decided to select 2 students randomly from the freshmen,5 randomly from the sophomores and 3 randomly from the juniors.This is an example of a systematic sample.

For a population frame containing N = 1,007 individuals,what code number should you assign to the first person on the list in order to use a table of random numbers?

The amount of bleach a machine pours into bottles has a mean of 36 oz.with a standard deviation of 0.15 oz.Suppose we take a random sample of 36 bottles filled by this machine.The probability that the mean of the sample is between 35.94 and 36.06 oz.is ________.

TABLE 7-5 According to a survey,only 15% of customers who visited the website of a major retail store made a purchase.Random samples of size 50 are selected. -A study at a college in the west coast reveals that,historically,45% of the students are minority students.If a random sample of size 75 is selected,the probability is ________ that more than half of the students in the sample will be minority students.

Which of the following can be reduced by proper interviewer training?

The mean of the sampling distribution of a sample proportion is the population proportion,π.

The standard error of the mean is also known as the standard deviation of the sampling distribution of the sample mean.

TABLE 7-2 The time spent studying by students in the week before final exams follows a normal distribution with a standard deviation of 8 hours.A random sample of 4 students was taken in order to estimate the mean study time for the population of all students. -Referring to Table 7-2,what is the probability that the sample mean differs from the population mean by more than 3 hours?

Since a ________ is not a randomly selected probability sample,there is no way to know how well it represents the overall population.

A sampling distribution is defined as the probability distribution of possible sample sizes that can be observed from a given population.

A sample that does not provide a good representation of the population from which it was collected is referred to as a(n)________ sample.

Major league baseball salaries averaged $3.26 million with a standard deviation of $1.2 million in a recent year.Suppose a sample of 100 major league players was taken.What was the standard error for the sample mean salary?

Sampling error can be reduced by taking larger sample sizes.