Question 1

A sample of size 25 is selected from a population of size 75.The finite population correction needed to find the standard error of  .

Accepted Answer

A) True 
 B)False

Question 2

The mean of the sampling distribution of the sample proportion  , when the sample size n = 100 and the population proportion p = 0.92, is 92.0.

Accepted Answer

A) True 
 B)False

Question 3

Magazines
A local magazine store sells an average of 2,100 magazines per day, with a standard deviation of 500 magazines.Consider a sample of 60 days of operation.
-{Magazines Narrative} What is the shape of the sampling distribution of the sample mean number of magazines sold per day? Why?

Accepted Answer

The answer of Magazines
A local magazine store sells an average...

Question 4

If all possible samples of size n are drawn from an infinite population with a mean of 15 and a standard deviation of 5, then the standard error of the sample mean equals 1.0 for samples of size:

Accepted Answer

A)  5 
B)  15 
C)  25 
D)  None of these choices.

Question 5

Retirees
A sample of 50 retirees is drawn at random from a normal population whose mean age and standard deviation are 75 and 6 years, respectively.
-{Retirees Narrative} What is the probability that the mean age exceeds 73 years?

Accepted Answer

The answer of Retirees
A sample of 50 retirees is drawn...

Question 6

Magazines
A local magazine store sells an average of 2,100 magazines per day, with a standard deviation of 500 magazines.Consider a sample of 60 days of operation.
-{Magazines Narrative} What is the probability that the sample mean is between 2,000 and 2,300 magazines?

Accepted Answer

The answer of Magazines
A local magazine store sells an average...

Question 7

Random samples of size 49 are taken from an infinite population whose mean is 300 and standard deviation is 21.The mean and standard error of the sample mean, respectively, are:

Accepted Answer

A)  300 and 21 
B)  300 and 3 
C)  300 and 0.43 
D)  None of these choices.

Question 8

Mean Salary
In order to estimate the mean salary for a population of 500 employees, the president of a certain company selected at random a sample of 40 employees.
-{Mean Salary Narrative} Would you use the finite population correction factor in calculating the standard error of the sample mean in this case? Explain.

Accepted Answer

The answer of Mean Salary
In order to estimate the mean...

Question 9

Given that X is a binomial random variable with very large n, the binomial probability P(X = 5) is approximated by the area under a normal curve between

Accepted Answer

A)  5 and 5 
B)  4 and 6 
C)  4.5 and 5.5 
D)  None of these choices.

Question 10

For sample sizes greater than 30, the sampling distribution of the mean is approximately normally distributed:

Accepted Answer

A)  regardless of the shape of the population. 
B)  only if the shape of the population is symmetric. 
C)  only if the population is normally distributed. 
D)  None of these choices.

Question 11

Suppose that the probability p of success on any trail of a binomial distribution equals 0.90.Then for which of the following number of trials, n, would the normal distribution provide a good approximation to the binomial distribution?

Accepted Answer

A)  35 
B)  45 
C)  55 
D)  All of these choices are true.

Question 12

Poker Time
The amount of time spent by American adults playing Poker per week is normally distributed with a mean of 4 hours and standard deviation of 1.25 hours.
-{Poker Time Narrative} Find the probability that if four American adults are randomly selected, their average number of hours spent playing Poker is more than 5 hours per week.

Accepted Answer

The answer of Poker Time
The amount of time spent by...

Question 13

As the size of the sample is increased, the standard error of  decreases.

Accepted Answer

A) True 
 B)False

Question 14

Suppose X has a distribution that is not normal.The Central Limit Theorem is important in this case because:

Accepted Answer

A)  it says the sampling distribution ofis approximately normal for any sample size. 
B)  it says the sampling distribution ofis approximately normal if n is large enough. 
C)  it says the sampling distribution ofis exactly normal, for any sample size. 
D)  None of these choices.

Question 15

The estimator of the probability of success in a binomial distribution is: ____________________.

Accepted Answer

The answer of The estimator of the probability of success...

Question 16

Heights of Men
The heights of men in the USA are normally distributed with a mean of 68 inches and a standard deviation of 4 inches.
-{Heights of Men Narrative} What is the probability that a randomly selected man is taller than 70 inches?

Accepted Answer

The answer of Heights of Men
The heights of men in...

Question 17

CFO's Salary
Suppose that the starting salaries of female CFO's have a positively skewed distribution with mean of $56,000 and a standard deviation of $12,000.The starting salaries of male CFO's are positively skewed with a mean of $50,000 and a standard deviation of $10,000.A random sample of 50 female CFO's and a random sample of 40 male CFO's are selected.
-{CFO's Salary Narrative} What is the probability that the sample mean salary of male CFO's will not exceed that of the female CFO's?

Accepted Answer

The answer of CFO's Salary
Suppose that the starting salaries of...

Question 18

A sample of 250 observations is selected at random from an infinite population.Given that the population proportion is .25, the standard error of the sampling distribution of the sample proportion is:

Accepted Answer

A)  0.0274 
B)  0.5000 
C)  0.0316 
D)  0.0548

Question 19

DVD Rental Store
A DVD rental store wants to know what proportion of its customers are under age 21.A simple random sample of 500 customers was taken, and 375 of them were under age 21.Presume that the true population proportion of customers under age 21 is 0.68.
-{DVD Rental Store Narrative} Describe the shape of the sampling distribution of proportion of customers who are under age 21.

Accepted Answer

The answer of DVD Rental Store
A DVD rental store wants...

Question 20

Barack Obama
Bill Clinton, the former President of the United States, believes that the proportion of voters who will vote for Barack Obama in the year 2012 presidential elections is 0.65.A sample of 500 voters is selected at random.
-{Barack Obama Narrative} Assume that Gore is correct and p = 0.65.What is the sampling distribution of the sample proportion  ? Explain.

Accepted Answer

The answer of Barack Obama
Bill Clinton, the former President of...

Exam 9: Sampling Distributions

A sample of size 25 is selected from a population of size 75.The finite population correction needed to find the standard error of .

The mean of the sampling distribution of the sample proportion , when the sample size n = 100 and the population proportion p = 0.92, is 92.0.

Magazines A local magazine store sells an average of 2,100 magazines per day, with a standard deviation of 500 magazines.Consider a sample of 60 days of operation. -{Magazines Narrative} What is the shape of the sampling distribution of the sample mean number of magazines sold per day? Why?

If all possible samples of size n are drawn from an infinite population with a mean of 15 and a standard deviation of 5, then the standard error of the sample mean equals 1.0 for samples of size:

Retirees A sample of 50 retirees is drawn at random from a normal population whose mean age and standard deviation are 75 and 6 years, respectively. -{Retirees Narrative} What is the probability that the mean age exceeds 73 years?

Magazines A local magazine store sells an average of 2,100 magazines per day, with a standard deviation of 500 magazines.Consider a sample of 60 days of operation. -{Magazines Narrative} What is the probability that the sample mean is between 2,000 and 2,300 magazines?

Random samples of size 49 are taken from an infinite population whose mean is 300 and standard deviation is 21.The mean and standard error of the sample mean, respectively, are:

Given that X is a binomial random variable with very large n, the binomial probability P(X = 5) is approximated by the area under a normal curve between

For sample sizes greater than 30, the sampling distribution of the mean is approximately normally distributed:

Suppose that the probability p of success on any trail of a binomial distribution equals 0.90.Then for which of the following number of trials, n, would the normal distribution provide a good approximation to the binomial distribution?

As the size of the sample is increased, the standard error of decreases.

Suppose X has a distribution that is not normal.The Central Limit Theorem is important in this case because:

The estimator of the probability of success in a binomial distribution is: ____________________.

Heights of Men The heights of men in the USA are normally distributed with a mean of 68 inches and a standard deviation of 4 inches. -{Heights of Men Narrative} What is the probability that a randomly selected man is taller than 70 inches?

A sample of 250 observations is selected at random from an infinite population.Given that the population proportion is .25, the standard error of the sampling distribution of the sample proportion is: