Question 1

Given that Z is a standard normal variable,the variance of Z:

Accepted Answer

A)  is always greater than 2.0. 
B)  is always greater than 1.0. 
C)  is always equal to 1.0. 
D)  cannot assume a specific value. 
A)  is always greater than 2.0. 
B)  is always greater than 1.0. 
C)  is always equal to 1.0. 
D)  cannot assume a specific value.

Question 2

Counter Sales
Suppose that customers arrive at a counter at an average rate of three customers per minute and that their arrivals follow the Poisson model.
-{Counter Sales Narrative} Use the appropriate exponential distribution to find the probability that the next customer will arrive within 1.5 minutes.

Accepted Answer

The answer of Counter Sales
Suppose that customers arrive at a...

Question 3

Battery Life
A certain brand of batteries has a lifetime that has a normal distribution with a mean of 3,750 hours and a standard deviation of 300 hours.
-{Battery Life Narrative} What proportion of these batteries will last between 3,800 and 4,100 hours?

Accepted Answer

The answer of Battery Life
A certain brand of batteries has...

Question 4

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} Find the waiting time at which only 10% of the customers will continue to hold.

Accepted Answer

P(X > x)= e ^-

Question 5

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 is the probability that a randomly selected caller is placed on hold for fewer than 6 minutes?

Accepted Answer

P(X < 6)= 1 -e<sup>-

Question 6

Diet
Researchers studying the effects of a new diet found that the weight loss over a one-month period by those on the diet was normally distributed with a mean of 10 pounds and a standard deviation of 5 pounds.
-{Diet Narrative} If a dieter is selected at random,what is the probability that the dieter lost more than 7.5 pounds?

Accepted Answer

The answer of Diet
Researchers studying the effects of a new...

Question 7

Suppose X has a chi-squared distribution with 10 degrees of freedom.The mean of X is:

Accepted Answer

A)  10 
B)  9 
C)  20 
D)  None of these choices. 
A)  10 
B)  9 
C)  20 
D)  None of these choices.

Question 8

The probability that Z is less than -2 is the same as one minus the probability that Z is greater than +2.

Accepted Answer

A) True 
 B)False

Question 9

Suppose Lamont's exam score was at the 80th percentile on an exam whose mean was 90.What was Lamont's exam score?

Accepted Answer

A)  76.81 
B)  72.00 
C)  80.00 
D)  Cannot tell without more information. 
A)  76.81 
B)  72.00 
C)  80.00 
D)  Cannot tell without more information.

Question 10

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 the...

Question 11

The mean of a Student t distribution is ____________________.

Accepted Answer

The answer of The mean of a Student t distribution...

Question 12

What number corresponds to t0.05,10?

Accepted Answer

A)  1.812 
B)  1.372 
C)  2.228 
D)  1.833 
A)  1.812 
B)  1.372 
C)  2.228 
D)  1.833

Question 13

The sum of all values of f(x)over the range of [a,b] must equal one.

Accepted Answer

A) True 
 B)False

Question 14

A random variable X is standardized by subtracting the mean and dividing by the variance.

Accepted Answer

A) True 
 B)False

Question 15

Which of the following represents a difference between continuous and discrete random variables?

Accepted Answer

A)  Continuous random variables assume an uncountable number of values,and discrete random variables do not. 
B)  The probability for any individual value of a continuous random variable is zero,but for discrete random variables it is not. 
C)  Probability for continuous random variables means finding the area under a curve,while for discrete random variables it means summing individual probabilities. 
D)  All of these choices are true. 
A)  Continuous random variables assume an uncountable number of values,and discrete random variables do not. 
B)  The probability for any individual value of a continuous random variable is zero,but for discrete random variables it is not. 
C)  Probability for continuous random variables means finding the area under a curve,while for discrete random variables it means summing individual probabilities. 
D)  All of these choices are true.

Question 16

Electronics Test
The time it takes a student to finish a electronics test has a uniform distribution between 50 and 70 minutes.
-{Electronics Test Narrative} Find the probability that a student will take exactly one hour to finish the test.

Accepted Answer

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

Question 17

The variance of a Student t distribution approaches zero as the degrees of freedom approaches infinity.

Accepted Answer

A) True 
 B)False

Question 18

Truck Salesman
A used truck salesman in a small town states that,on the average,it takes him 5 days to sell a truck.Assume that the probability distribution of the length of time between sales is exponentially distributed.
-{Truck Salesman Narrative} What is the probability that he will have to wait between 6 and 10 days before making another sale?

Accepted Answer

The answer of Truck Salesman
A used truck salesman in a...

Question 19

The F distribution has two parameters called degrees of freedom,$\nu$1 and $\nu$2.We call $\nu$1 the ____________________ degrees of freedom,and we call $\nu$2 the ____________________ degrees of freedom.

Accepted Answer

numerator;

Question 20

For a continuous random variable,the probability for each individual value of X is ____________________.

Accepted Answer

The answer of For a continuous random variable,the probability for...

Exam 8: Continuous Probability Distributions

Given that Z is a standard normal variable,the variance of Z:

Battery Life A certain brand of batteries has a lifetime that has a normal distribution with a mean of 3,750 hours and a standard deviation of 300 hours. -{Battery Life Narrative} What proportion of these batteries will last between 3,800 and 4,100 hours?

Suppose X has a chi-squared distribution with 10 degrees of freedom.The mean of X is:

The probability that Z is less than -2 is the same as one minus the probability that Z is greater than +2.

Suppose Lamont's exam score was at the 80th percentile on an exam whose mean was 90.What was Lamont's exam score?

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?

The mean of a Student t distribution is ____________________.

What number corresponds to t0.05,10?

The sum of all values of f(x)over the range of [a,b] must equal one.

A random variable X is standardized by subtracting the mean and dividing by the variance.

Which of the following represents a difference between continuous and discrete random variables?

Electronics Test The time it takes a student to finish a electronics test has a uniform distribution between 50 and 70 minutes. -{Electronics Test Narrative} Find the probability that a student will take exactly one hour to finish the test.

The variance of a Student t distribution approaches zero as the degrees of freedom approaches infinity.

The F distribution has two parameters called degrees of freedom, ν\nuν 1 and ν\nuν 2.We call ν\nuν 1 the ____________________ degrees of freedom,and we call ν\nuν 2 the ____________________ degrees of freedom.

For a continuous random variable,the probability for each individual value of X is ____________________.

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

Sampling 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

Suppose Lamont's exam score was at the 80^th percentile on an exam whose mean was 90.What was Lamont's exam score?

What number corresponds to t_0.05,10?

The F distribution has two parameters called degrees of freedom, $\nu$ ₁ and $\nu$ ₂.We call $\nu$ ₁ the degrees of freedom,and we call $\nu$ ₂ the degrees of freedom.