Question 1

Which of the following statements is true?

Accepted Answer

A) The chi-squared distribution is positively skewed. 
B) All the values of the chi-squared distribution are non-negative. 
C) The shape of the chi-squared distribution depends on its degrees of freedom. 
D) All of these choices are true. 
A) The chi-squared distribution is positively skewed. 
B) All the values of the chi-squared distribution are non-negative. 
C) The shape of the chi-squared distribution depends on its degrees of freedom. 
D) All of these choices are true.

Question 2

The mean and the variance of an exponential distribution are equal to each other.

Accepted Answer

A) True 
 B)False

Question 3

Waiting Time 
The length of time patients must wait to see a doctor at an emergency room in a large hospital has a uniform distribution between 40 minutes and 3 hours. ​ ​
-{Waiting Time Narrative} What is the probability that a patient would have to wait between one and two hours?

Accepted Answer

The answer of  Waiting Time 
The length of time...

Question 4

Tanner took a statistics test whose mean was 80 and standard deviation was 5.The total points possible was 100.Tanner's score was 2 standard deviations below the mean.What was Tanner's score,rounded to the nearest whole number?

Accepted Answer

A) 78 
B) 70 
C) 90 
D) None of these choices. 
A) 78 
B) 70 
C) 90 
D) None of these choices.

Question 5

Use the x2 table to find the following probabilities.
a.  
b.  
c.  
d.

Accepted Answer

a. 0.900

Question 6

A random variable with density function 0.01e−x/100 for x ≥ 0 has an exponential distribution whose mean is ____________________.

Accepted Answer

Question 7

A random variable X has a normal distribution with a mean of 250 and a standard deviation of 50.Given that X = 175,its corresponding value of Z is −1.50.

Accepted Answer

A) True 
 B)False

Question 8

IT Graduates Salary 
The recent average starting salary for new college graduates in IT systems is $47,500.Assume salaries are normally distributed with a standard deviation of $4,500. ​ ​
-{IT Graduates Salary Narrative} What percent of starting salaries are no more than $42,250?

Accepted Answer

The answer of  IT Graduates Salary 
The recent average...

Question 9

Subway Waiting Time 
At a subway station the waiting time for a subway is found to be uniformly distributed between 1 and 5 minutes. ​ ​
-{Subway Waiting Time Narrative} What is the median waiting time for this subway?

Accepted Answer

The answer of Subway Waiting Time 
At a subway station...

Question 10

As the ____________________ degrees of freedom increase,the mean of the F distribution approaches 1.

Accepted Answer

The answer of As the ____________________ degrees of freedom increase,the...

Question 11

The probability density function f(x)of a random variable X that has a uniform distribution between a and b is

Accepted Answer

A) (b + a)/2 
B) 1/b − 1/a 
C) (a − b)/2 
D) None of these choices. 
A) (b + a)/2 
B) 1/b − 1/a 
C) (a − b)/2 
D) None of these choices.

Question 12

Electronics Test
the time it takes a student to finish a electronics test has a uniform distrubtion between 50 and 70 minutes.
-{Electronics Test Narrative} Find the probability that a student will take no less than 55 minutes to finish the test.

Accepted Answer

The answer of Electronics Test
the time it takes a student...

Question 13

Suppose you have an F distribution with degrees of freedom 10,20.
a.Find the mean
b.Find the variance.
c.Find the standard deviation.

Accepted Answer

a. 20/18 = 1.11 
b.

Question 14

P(Z > 1.9)= ____________________ P(Z < 1.9).

Accepted Answer

The answer of P(Z > 1.9)= ____________________ P(Z < 1.9)....

Question 15

The Student t distribution looks similar in shape to a standard normal distribution,except it is not as widely spread.

Accepted Answer

A) True 
 B)False

Question 16

If the random variable X is exponentially distributed with parameter λ = 0.05,then the probability P(X > 20)= 0.3679.

Accepted Answer

A) True 
 B)False

Question 17

Phone Orders
 The L.L.Bean catalog department that receives the majority of its orders by telephone conducted a study to determine how long customers were willing to wait on hold before ordering a product.The length of time was found to be a random variable best approximated by an exponential distribution with a mean equal to 3 minutes.
-{Phone Orders Narrative} What proportion of callers are put on hold longer than 3 minutes?

Accepted Answer

P(X > 3)=

Question 18

Which of the following can have an exponential distribution?

Accepted Answer

A) Time between phone calls coming in to a technical support desk. 
B) Time until the first customer arrives at the bank in the morning. 
C) Lifetime of a new battery. 
D) All of these choices are true. 
A) Time between phone calls coming in to a technical support desk. 
B) Time until the first customer arrives at the bank in the morning. 
C) Lifetime of a new battery. 
D) All of these choices are true.

Question 19

What number corresponds to F.025,3,5?

Accepted Answer

A) 14.88 
B) 7.76 
C) 12.06 
D) 5.41 
A) 14.88 
B) 7.76 
C) 12.06 
D) 5.41

Question 20

Checking Accounts 
A bank has determined that the monthly balances of the checking accounts of its customers are normally distributed with an average balance of $1,200 and a standard deviation of $250. ​ ​
-{Checking Accounts Narrative} What proportion of customers have monthly balances between $950 and $1,075?

Accepted Answer

The answer of Checking Accounts 
A bank has determined that...

Exam 8: Continuous Probability Distributions

Which of the following statements is true?

The mean and the variance of an exponential distribution are equal to each other.

Waiting Time The length of time patients must wait to see a doctor at an emergency room in a large hospital has a uniform distribution between 40 minutes and 3 hours. ​ ​ -{Waiting Time Narrative} What is the probability that a patient would have to wait between one and two hours?

Tanner took a statistics test whose mean was 80 and standard deviation was 5.The total points possible was 100.Tanner's score was 2 standard deviations below the mean.What was Tanner's score,rounded to the nearest whole number?

Use the x2 table to find the following probabilities. a. b. c. d.

A random variable with density function 0.01e−x/100 for x ≥ 0 has an exponential distribution whose mean is ____________________.

A random variable X has a normal distribution with a mean of 250 and a standard deviation of 50.Given that X = 175,its corresponding value of Z is −1.50.

IT Graduates Salary The recent average starting salary for new college graduates in IT systems is $47,500.Assume salaries are normally distributed with a standard deviation of $4,500. ​ ​ -{IT Graduates Salary Narrative} What percent of starting salaries are no more than $42,250?

Subway Waiting Time At a subway station the waiting time for a subway is found to be uniformly distributed between 1 and 5 minutes. ​ ​ -{Subway Waiting Time Narrative} What is the median waiting time for this subway?

As the ____________________ degrees of freedom increase,the mean of the F distribution approaches 1.

The probability density function f(x)of a random variable X that has a uniform distribution between a and b is

Electronics Test the time it takes a student to finish a electronics test has a uniform distrubtion between 50 and 70 minutes. -{Electronics Test Narrative} Find the probability that a student will take no less than 55 minutes to finish the test.

Suppose you have an F distribution with degrees of freedom 10,20. a.Find the mean b.Find the variance. c.Find the standard deviation.

P(Z > 1.9)= ____________________ P(Z < 1.9).

The Student t distribution looks similar in shape to a standard normal distribution,except it is not as widely spread.

If the random variable X is exponentially distributed with parameter λ = 0.05,then the probability P(X > 20)= 0.3679.

Which of the following can have an exponential distribution?

What number corresponds to F.025,3,5?

What Is Statistics

Graphical Descriptive Techniques 1

Graphical Descriptive Techniques 2

Numerical Descriptive Techniques

Data Collection and Sampling

Probability

Random Variables and Discrete Probability Distributions

Sampling Distributions

Introduction to Estimation

Introduction to Hypothesis Testing

Inference About a Population

Inference About Comparing Two Populations

Analysis of Variance

Chi-Squared Tests

Simple Linear Regression and Correlation

Multiple Regression

Model Building

Nonparametric Statistics

Time-Series Analytics and Forecasting

Statistical Process Control

Decision Analysis

Conclusion

Filters

Waiting Time The length of time patients must wait to see a doctor at an emergency room in a large hospital has a uniform distribution between 40 minutes and 3 hours. -{Waiting Time Narrative} What is the probability that a patient would have to wait between one and two hours?

Use the x² table to find the following probabilities. a. b. c. d.

A random variable with density function 0.01e−x^/100 for x ≥ 0 has an exponential distribution whose mean is ____________________.

IT Graduates Salary The recent average starting salary for new college graduates in IT systems is $47,500.Assume salaries are normally distributed with a standard deviation of $4,500. -{IT Graduates Salary Narrative} What percent of starting salaries are no more than $42,250?

Subway Waiting Time At a subway station the waiting time for a subway is found to be uniformly distributed between 1 and 5 minutes. -{Subway Waiting Time Narrative} What is the median waiting time for this subway?

What number corresponds to F_.025,3,5?