When comparing two population means with an unknown standard deviation

Question 1 of 12 10.0 Points

When comparing two population means with an unknown standard deviation you use a t test and you use n-1 degrees of freedom.

A. True

B. False

Question 2 of 12 10.0 Points

Pretend you want to determine whether the mean weekly sales of soup are the same when the soup is the featured item and when it is a normal item on the menu. When it is the featured item the sample mean is 55 and the population standard deviation is 3 with a sample size of 23. When it is a normal item the sample mean is 53 with a standard deviation of 4 and a sample size of 7. Given this information we could use a t test for two independent means.

A. True

B. False

Question 3 of 12 10.0 Points

The null hypothesis can be proven if it is rejected.

A. True

 B. False

Question 4 of 12 10.0 Points

For 2 sample tests of independence of population means we compare sample means to run our hypothesis test.

A. True

 B. False

Question 5 of 12 10.0 Points

You want to determine if your widgets from machine 1 are the same as machine 2. Machine 1 has a sample mean of 50 and a population standard deviation 5 and a sample size of 25. Machine 2 has a sample mean of 52 and a population standard deviation of 6 with a sample size of 12. With an alpha of .10 can we claim that there is a difference between the output of the two machines. Which of the following statements are true?

 A. We will reject the null hypothesis and prove there is a difference between the 2 populations 

B. We will not reject the null hypothesis and thus we can’t prove there is difference between the 2 populations

 C. The critical values you will use are 1.96 and -1.96 

 D. B and C are correct 

 E. None of the above are correct

Question 6 of 12 10.0 Points

You want to determine if your widgets from machine 1 are the same as machine 2. Machine 1 has a sample mean of 50 and a population standard deviation 5 and a sample size of 25. Machine 2 has a sample mean of 52 and a population standard deviation of 6 with a sample size of 12. We have an alpha of .01. Which of the following statements is true.

A. We use 2.58 and -2.58 as our critical values

 B. We will use a t test 

 C. We use 1.28 and -1.28 as our critical values 

 D. A and B are correct 

 E. None of the above are correct 

 Question 7 of 12 10.0 Points

You want to determine if your widgets from machine 1 are the same as machine 2. Machine 1 has a sample mean of 500 and a population standard deviation 6 and a sample size of 18. Machine 2 has a sample mean of 500.5 and a population standard deviation of 2 with a sample size of 2. With an alpha of .05 can we claim that there is a difference between the output of the two machines. Which of the following statements are true?

A. We will reject the null hypothesis and prove there is a difference between the 2 populations 

 B. We will not reject the null hypothesis and thus we can’t prove there is difference between the 2 populations 

 C. The critical values you will use are 1.96 and -1.96 

D. B and C are correct

 E. None of the above are correct 

Question 8 of 12 10.0 Points

You want to determine if your widgets from machine 1 are the same as machine 2. Machine 1 has a sample mean of 5 and a population standard deviation 1 and a sample size of 4. Machine 2 has a sample mean of 8 and a population standard deviation of 2 with a sample size of 4. With an alpha of .05 can we claim that there is a difference between the output of the two machines. Which of the following statements are true?

A. We will reject the null hypothesis and prove there is a difference between the 2 populations

 B. We will not reject the null hypothesis and thus we can’t prove there is difference between the 2 populations 

 C. The critical values you will use are 1.96 and -1.96 

 D. A and C are correct 

 E. None of the above are correct 

Question 9 of 12 10.0 Points

You want to determine if your widgets from machine 1 are the same as machine 2. Machine 1 has a sample mean of 15 and a population standard deviation 5 and a sample size of 12.5. Machine 2 has a sample mean of 9 and a population standard deviation of 6 with a sample size of 12. With an alpha of .01 can we claim that there is a difference between the output of the two machines. Which of the following statements are true?

A. We will reject the null hypothesis and prove there is a difference between the 2 populations

 B. We will not reject the null hypothesis and thus we can’t prove there is difference between the 2 populations 

 C. The critical values you will use are 1.96 and -1.96 

D. B and C are correct 

E. None of the above are correct 

Question 10 of 12 10.0 Points

You want to determine if your widgets from machine 1 are the same as machine 2. Machine 1 has a sample mean of 15 and a population standard deviation 5 and a sample size of 12.5. Machine 2 has a sample mean of 12 and a population standard deviation of 6 with a sample size of 12. With an alpha of .05 can we claim that there is a difference between the output of the two machines. Which of the following statements are true?

 A. We will reject the null hypothesis and prove there is a difference between the 2 populations 

 B. We will not reject the null hypothesis and thus we can’t prove there is difference between the 2 populations 

 C. The critical values you will use are 1.96 and -1.96 

D. B and C are correct

 E. None of the above are correct 

Question 11 of 12 10.0 Points

You want to determine if your widgets from machine 1 are the same as machine 2. Machine 1 has a sample mean of 15 and a sample standard deviation 6 and a sample size of 18. Machine 2 has a sample mean of 12 and a sample standard deviation of 6 with a sample size of 18. With an alpha of .05 can we claim that there is a difference between the output of the two machines. Which of the following statements are true?

 A. We will reject the null hypothesis and prove there is a difference between the 2 populations 

 B. We will not reject the null hypothesis and thus we can’t prove there is difference between the 2 populations 

C. The critical values you will use are 1.96 and -1.96 

D. B and C are correct

 E. None of the above are correct 

Question 12 of 12 10.0 Points

You want to determine if your widgets from machine 1 are the same as machine 2. Machine 1 has a sample mean of 15 and a sample standard deviation 6 and a sample size of 2. Machine 2 has a sample mean of 12 and a sample standard deviation of 6 with a sample size of 2. With an alpha of .05 can we claim that there is a difference between the output of the two machines. Which of the following statements are true?

 A. We will reject the null hypothesis and prove there is a difference between the 2 populations 

B. We will not reject the null hypothesis and thus we can’t prove there is difference between the 2 populations

 C. The critical values you will use are 1.96 and -1.96 

 D. B and C are correct 

 E. None of the above are correct