Question 1

The value of A such that P(-A $\le$ t $\le$ A) = 0.95, where the degrees of freedom are 20, is 2.086.

Accepted Answer

A) True 
 B)False

Question 2

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.
-What is the cutoff for the top 3% of the salaries?

Accepted Answer

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

Question 3

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.
-What proportion of the dieters lost more than 12 pounds?

Accepted Answer

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

Question 4

Like that of the Student t distribution, the shape of the chi-squared distribution depends on its number of degrees of freedom.

Accepted Answer

A) True 
 B)False

Question 5

The variance of a Student t distribution approaches ____________________ as the degrees of freedom increase to infinity.

Accepted Answer

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

Question 6

If  , then the number of degrees of freedom v is:

Accepted Answer

A)  5 
B)  6 
C)  7 
D)  8

Question 7

Which of the following has a mean and variance that depend on degrees of freedom?

Accepted Answer

A)  Student t 
B)  $\chi$2 
C)  F 
D)  All of these choices are true.

Question 8

Suppose X has an F distribution. Which of the following is true?

Accepted Answer

A)  f(x) is symmetrical. 
B)  All the values of X are non-negative. 
C)  The mean of X is zero. 
D)  All of these choices.

Question 9

Electronics Test: The time it takes a student to finish a electronics test has a uniform distribution between 50 and 70 minutes.
-Find the probability that a student will take more than 60 minutes to finish the test.

Accepted Answer

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

Question 10

Since there is an infinite number of values a continuous random variable can assume, the probability of each individual value is virtually 0.

Accepted Answer

A) True 
 B)False

Question 11

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.
-What is the probability of a new graduate getting a starting salary in excess of $55,000?

Accepted Answer

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

Question 12

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.
-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 13

Electronics Test: The time it takes a student to finish a electronics test has a uniform distribution between 50 and 70 minutes.
-What is the probability density function for this uniform distribution?

Accepted Answer

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

Question 14

If a point y lies outside the range of the possible values of a random variable X, then f(y) must equal zero.

Accepted Answer

A) True 
 B)False

Question 15

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.
-What proportion of these batteries will last less than 3,600 hours?

Accepted Answer

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

Question 16

A random variable X has a normal distribution with mean 132 and variance 36. If x = 120, its corresponding value of Z is 2.0.

Accepted Answer

A) True 
 B)False

Question 17

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 18

Stacy took a math test whose mean was 70 and standard deviation was 5. The total points possible was 100. Stacey's results were reported to be at the 95th percentile. What was Stacey's actual exam score, rounded to the nearest whole number?

Accepted Answer

A)  95 
B)  78 
C)  75 
D)  62

Question 19

The Student t distribution with parameter v = 4 has a variance V(t) equal to:

Accepted Answer

A)  4 
B)  0 
C)  2 
D)  1

Question 20

If we standardize the normal curve, we express the original X values in terms of their number of standard deviations away from the mean.

Accepted Answer

A) True 
 B)False

Exam 7: Continuous Probability Distributions

The value of A such that P(-A ≤\le≤ t ≤\le≤ A) = 0.95, where the degrees of freedom are 20, is 2.086.

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. -What is the cutoff for the top 3% of the salaries?

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. -What proportion of the dieters lost more than 12 pounds?

Like that of the Student t distribution, the shape of the chi-squared distribution depends on its number of degrees of freedom.

The variance of a Student t distribution approaches ____________________ as the degrees of freedom increase to infinity.

If , then the number of degrees of freedom v is:

Which of the following has a mean and variance that depend on degrees of freedom?

Suppose X has an F distribution. Which of the following is true?

Electronics Test: The time it takes a student to finish a electronics test has a uniform distribution between 50 and 70 minutes. -Find the probability that a student will take more than 60 minutes to finish the test.

Since there is an infinite number of values a continuous random variable can assume, the probability of each individual value is virtually 0.

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. -What is the probability of a new graduate getting a starting salary in excess of $55,000?

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. -What proportion of these batteries will last between 3,800 and 4,100 hours?

Electronics Test: The time it takes a student to finish a electronics test has a uniform distribution between 50 and 70 minutes. -What is the probability density function for this uniform distribution?

If a point y lies outside the range of the possible values of a random variable X, then f(y) must equal zero.

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. -What proportion of these batteries will last less than 3,600 hours?

A random variable X has a normal distribution with mean 132 and variance 36. If x = 120, its corresponding value of Z is 2.0.

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

Stacy took a math test whose mean was 70 and standard deviation was 5. The total points possible was 100. Stacey's results were reported to be at the 95th percentile. What was Stacey's actual exam score, rounded to the nearest whole number?

The Student t distribution with parameter v = 4 has a variance V(t) equal to:

If we standardize the normal curve, we express the original X values in terms of their number of standard deviations away from the mean.

The value of A such that P(-A $\le$ t $\le$ A) = 0.95, where the degrees of freedom are 20, is 2.086.