Question 1

In general,the binomial probability P(X $\ge$ x)is approximated by the area under the normal curve to the left of x - .5.

Accepted Answer

A) True 
 B)False

Question 2

The expected value of the sampling distribution of the sample mean $\bar { X }$ equals the population mean $\mu$ :

Accepted Answer

A)  only when the population is normally distributed. 
B)  only when the sample size is large. 
C)  only when the population is infinite. 
D)  for all populations. 
A)  only when the population is normally distributed. 
B)  only when the sample size is large. 
C)  only when the population is infinite. 
D)  for all populations.

Question 3

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

Question 4

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} Find the expected value and the standard deviation of the sample proportion $\hat { p }$ .

Accepted Answer

E( @#LAT-DLM& )= 0.6

Question 5

Average Annual Revenue
Suppose that the average annual revenue of a small business is $150,000 with a standard deviation of $40,000.Assume that the revenue distribution is normal.
-{Average Annual Revenue Narrative} Why are your answers to the previous two questions different?

Accepted Answer

The revenue of one business chosen from

Question 6

As a general rule,the normal distribution is used to approximate the sampling distribution of the sample proportion only if:

Accepted Answer

A)  the sample size n is greater than 30. 
B)  the population proportion p is close to 0.50. 
C)  the underlying population is normal. 
D)  np and n(1 - p)are both greater than or equal to 5. 
A)  the sample size n is greater than 30. 
B)  the population proportion p is close to 0.50. 
C)  the underlying population is normal. 
D)  np and n(1 - p)are both greater than or equal to 5.

Question 7

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 a randomly selected American adult plays Poker for more than 5 hours per week.

Accepted Answer

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

Question 8

In general,the binomial probability P(X = x)is approximated by the area under a normal curve between x +.5 and x + .5.

Accepted Answer

A) True 
 B)False

Question 9

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

Since np @#LAT-DLM& 5,and n(1

Question 10

Number of Fish Tanks
The following data give the number of fish tanks owned for a population of 4 families.
 $$\begin{array} { | l | c c c c | } 
\hline \text { Family } & \text { A } & \text { B } & \text { C } & \text { D } \
\hline \text { Number af Fish Tanks Owned } & 2 & 1 & 4 & 3 \
\hline
\end{array}$$
-{Number of Fish Tanks Narrative} Find the mean and the standard deviation for the population.

Accepted Answer

@#LAT-DLM&= 2.5 fish

Question 11

The amount of bleach a machine pours into bottles has a mean of 50 ounces with a standard deviation of 0.25 ounces.We take a random sample of 36 bottles filled by this machine.The sampling distribution of the sample mean has a mean of 50 ounces.

Accepted Answer

A) True 
 B)False

Question 12

As n gets larger,the sampling distribution of $\bar { X }$ becomes increasingly bell shaped.This phenomenon is due to the ____________________.

Accepted Answer

Central Li

Question 13

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} Find the mean and standard deviation of $\hat { p }$ .

Accepted Answer

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

Question 14

Temporary Worker Productivity
A temporary worker productivity is normally distributed.One worker produces an average of 84 units per day with a standard deviation of 24.Another worker produces at an average rate of 74 per day with a standard deviation of 25.
-{Temporary Worker Productivity Narrative} What is the probability that during one week (5 working days),worker 1 will outproduce worker 2 on average?

Accepted Answer

The answer of Temporary Worker Productivity
A temporary worker productivity is...

Question 15

The amount of time it takes to complete a final examination is negatively skewed distribution with a mean of 70 minutes and a standard deviation of 8 minutes.If 64 students were randomly sampled,the probability that the sample mean of the sampled students exceeds 73.5 minutes is approximately 0.

Accepted Answer

A) True 
 B)False

Question 16

The standard error of the sampling distribution of the sample proportion $\hat { p }$ ,when the sample size n = 100 and the population proportion p = 0.30,is 0.0021.

Accepted Answer

A) True 
 B)False

Question 17

In inferential statistics,the standard error of the sample mean assesses the uncertainty or error of estimation.

Accepted Answer

A) True 
 B)False

Question 18

A sample of size 200 is taken at random from an infinite population.Given that the population proportion is 0.60,the probability that the sample proportion is greater than 0.58 is:

Accepted Answer

A)  0.281 
B)  0.719 
C)  0.580 
D)  0.762 
A)  0.281 
B)  0.719 
C)  0.580 
D)  0.762

Question 19

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

Question 20

If all possible samples of size n are drawn from a normal population,the probability distribution of the sample mean $\bar { X }$ is an normal distribution.

Accepted Answer

A) True 
 B)False

Exam 9: Sampling Distributions

In general,the binomial probability P(X ≥\ge≥ x)is approximated by the area under the normal curve to the left of x - .5.

The expected value of the sampling distribution of the sample mean Xˉ\bar { X }Xˉ equals the population mean μ\muμ :

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?

Average Annual Revenue Suppose that the average annual revenue of a small business is $150,000 with a standard deviation of $40,000.Assume that the revenue distribution is normal. -{Average Annual Revenue Narrative} Why are your answers to the previous two questions different?

As a general rule,the normal distribution is used to approximate the sampling distribution of the sample proportion only if:

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 a randomly selected American adult plays Poker for more than 5 hours per week.

In general,the binomial probability P(X = x)is approximated by the area under a normal curve between x +.5 and x + .5.

Number of Fish Tanks The following data give the number of fish tanks owned for a population of 4 families. Family A B C D Number af Fish Tanks Owned 2 1 4 3 -{Number of Fish Tanks Narrative} Find the mean and the standard deviation for the population.

The amount of bleach a machine pours into bottles has a mean of 50 ounces with a standard deviation of 0.25 ounces.We take a random sample of 36 bottles filled by this machine.The sampling distribution of the sample mean has a mean of 50 ounces.

As n gets larger,the sampling distribution of Xˉ\bar { X }Xˉ becomes increasingly bell shaped.This phenomenon is due to the ____________________.

The amount of time it takes to complete a final examination is negatively skewed distribution with a mean of 70 minutes and a standard deviation of 8 minutes.If 64 students were randomly sampled,the probability that the sample mean of the sampled students exceeds 73.5 minutes is approximately 0.

The standard error of the sampling distribution of the sample proportion p^\hat { p }p^​ ,when the sample size n = 100 and the population proportion p = 0.30,is 0.0021.

In inferential statistics,the standard error of the sample mean assesses the uncertainty or error of estimation.

A sample of size 200 is taken at random from an infinite population.Given that the population proportion is 0.60,the probability that the sample proportion is greater than 0.58 is:

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:

If all possible samples of size n are drawn from a normal population,the probability distribution of the sample mean Xˉ\bar { X }Xˉ is an normal distribution.

What Is Statistics

Graphical Descriptive Techniques I

Graphical Descriptive Techniques II

A: Numerical Descriptive Techniques

B: Numerical Descriptive Techniques

C: Numerical Descriptive Techniques

Data Collection and Sampling

Probability

A: Random Variables and Discrete Probability Distributions

B: Random Variables and Discrete Probability Distributions

Continuous Probability Distributions

Introduction to Estimation

Introduction to Hypothesis Testing

Inference About a Population

Inference About Comparing Two Populations

Analysis of Variance

Chi-Squared Tests

A: Simple Linear Regression and Correlation

B: Simple Linear Regression and Correlation

Multiple Regression

Model Building

Nonparametric Statistics

Time-Series Analysis and Forecasting

Statistical Process Control

Decision Analysis

Conclusion

Filters

In general,the binomial probability P(X $\ge$ x)is approximated by the area under the normal curve to the left of x - .5.

The expected value of the sampling distribution of the sample mean $\bar { X }$ equals the population mean $\mu$ :

As n gets larger,the sampling distribution of $\bar { X }$ becomes increasingly bell shaped.This phenomenon is due to the ____________________.

The standard error of the sampling distribution of the sample proportion $\hat { p }$ ,when the sample size n = 100 and the population proportion p = 0.30,is 0.0021.

If all possible samples of size n are drawn from a normal population,the probability distribution of the sample mean $\bar { X }$ is an normal distribution.