Question

Question 12 (1 point)

The owner of a golf course wants to determine if his golf course is more difficult than the one his friend owns. He has 9 golfers play a round of 18 holes on his golf course and records their scores. Later that week, he has the same 9 golfers play a round of golf on his friend's course and records their scores again. The average difference in the scores (treated as the scores on his course - the scores on his friend's course) is 5.394 and the standard deviation of the differences is 11.7418. Calculate a 90% confidence interval to estimate the average difference in scores between the two courses.

Question 12 options:

1)	(3.5345, 7.2535)

2)	(1.4801, 9.3079)

3)	(1.8841, 12.6721)

4)	(-1.7807, 12.5687)

5)	(-1.8841, 12.6721)

Question 13 (1 point)

A new drug to treat high cholesterol is being tested by pharmaceutical company. The cholesterol levels for 38 patients were recorded before administering the drug and after. The 99% confidence interval for the true mean difference in total cholesterol levels (after - before) was (-48.54, -3.06). Which of the following is the appropriate conclusion?

Question 13 options:

1)	We are 99% confident that the average difference in cholesterol levels is positive, with the higher cholesterol levels being before the drug regimen.

2)	We are 99% confident that the average difference in cholesterol levels is positive, with the higher cholesterol levels being after the drug regimen.

3)	We are 99% confident that the average difference in cholesterol levels is negative, with the higher cholesterol levels being after the drug regimen.

4)	There is not a significant difference in average cholesterol levels before and after the drug.

5)	We are 99% confident that the average difference in cholesterol levels is negative, with the higher cholesterol levels being before the drug regimen.

Question 14 (1 point)

Automobile manufacturers are interested in the difference in reaction times for drivers reacting to traditional incandescent lights and to LED lights. A sample of 22 drivers are told to press a button as soon as they see a light flash in front of them and the reaction time was measured in milliseconds. Each driver was shown each type of light. The average difference in reaction times (traditional - LED) is 0.5 ms with a standard deviation of 7.39 ms. A 90% confidence interval for the average difference between the two reaction times was (-2.21, 3.21). Which of the following is the best interpretation?

Question 14 options:

1)	The proportion of all drivers that had a difference in reaction times between the two lights is 90%.

2)	We are certain the average difference in reaction times between the two light types for all drivers is between -2.21 and 3.21.

3)	We are 90% confident that the average difference in reaction time between the two light types for all drivers is between -2.21 and 3.21.

4)	We are 90% confident that the difference between the average reaction time for LED lights and the average reaction time for traditional lights is between -2.21 and 3.21.

5)	We are 90% confident that the average difference in the reaction times of the drivers sampled is between -2.21 and 3.21.

Answer 1

12)

sample mean 'x̄=	5.394
sample size   n=	9.00
sample std deviation s=	11.742
std error 'sx=s/√n=	3.9139

for 90% CI; and 8 df, value of t=		1.860
margin of error E=t*std error    =		7.28
lower bound=sample mean-E =		-1.89
Upper bound=sample mean+E =		12.67

correct option is:

5) (-1.8841, 12.672 )

13)

Correct option is (5)

We are 99% confident that the average difference in cholesterol levels is negative, with the higher cholesterol levels being before the drug regimen
14)

option 3) is correct

We are 90% confident that the average difference in reaction time between the two light types for all drivers is between -2.21 and 3.21.