Question

Question 5 (1 point)

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A U.S. census bureau pollster noted that in 447 random households surveyed, 290 occupants owned their own home. What is the 99% confidence interval estimate of the proportion of American households who own their own home?

Question 5 options:

	1) ( 0.62619 , 0.67135 )
	2) ( 0.59061 , 0.70693 )
	3) ( 0.59625 , 0.70129 )
	4) ( -0.59061 , 0.70693 )
	5) ( 0.29307 , 0.40939 )

Question 6 (1 point)

You work for a pharmaceutical company that is testing a new cholesterol drug. The proportion of patients on the previous drug who had a positive treatment was 0.414. You want to see if the new drug is more effective than the previous drug. You conduct a sample of 116 patients on the new drug and find that 81 have had a positive treatment effect. The 99% confidence interval is ( 0.5885 , 0.8081 ). What is the best conclusion you can make of those listed below?

Question 6 options:

	1) We can conclude that the proportion of patients who see a positive treatment effect with the new drug is smaller than 0.414.
	2) The confidence interval does not provide enough information to form a conclusion.
	3) We can claim that the proportion of patients who see a positive treatment effect with the new drug is larger than 0.414.
	4) We can not claim that the proportion of patients who see a positive treatment effect with the new drug differs from 0.414.
	5) The proportion of patients on the new drug who saw a positive treatment effect from 0.414 is 99%.

Question 7 (1 point)

In a packing plant, one of the machines packs jars into a box. A sales rep for a packing machine manufacturer comes into the plant saying that a new machine he is selling will pack the jars faster than the old machine. To test this claim, each machine is timed for how long it takes to pack 10 cartons of jars at randomly chosen times. Given a 95% confidence interval of (-8.73, -2.65) for the true difference in average times to pack the jars (old machine - new machine), what can you conclude from this interval?

Question 7 options:

	1) We do not have enough information to make a conclusion.
	2) There is no significant difference between the average packing times of the two machines. The sales rep does not appear to be telling the truth.
	3) We are 95% confident that the difference between the two sample means falls within the interval.
	4) We are 95% confident that the average packing time of the old machine is greater than the new machine. The sales rep appears to be correct.
	5) We are 95% confident that the average packing time of the new machine is greater than the old machine. The sales rep does not appear to be telling the truth.

Question 8 (1 point)

Researchers in the corporate office of an airline wonder if there is a significant difference between the cost of a flight on Priceline.com vs. the airline's own website. A random sample of 20 flights were tracked on Priceline and the airline's website and the average difference between the vendors was $4.294 with a standard deviation of $5.3109. The 99% confidence paired-t interval for price (Priceline - Airline Site) was (0.8965, 7.6915). Which of the following is the appropriate interpretation?

Question 8 options:

	1) We are certain the average difference in prices between the two vendors for all flights is between 0.8965 and 7.6915.
	2) The proportion of all flights that had a difference in price between the two vendors is 99%.
	3) We are 99% confident that the difference between the average price on Priceline and the average price on the airline's website is between 0.8965 and 7.6915.
	4) We are 99% confident that the average difference in the prices of the flights sampled is between 0.8965 and 7.6915.
	5) We are 99% confident that the average difference in price between the two vendors for all flights is between 0.8965 and 7.6915.

Answer 1

Question 5 (1 point)

A U.S. census bureau pollster noted that in 447 random households surveyed, 290 occupants owned their own home. What is the 99% confidence interval estimate of the proportion of American households who own their own home?

Correct Answer:

2)

( 0.59061 , 0.70693 )

Question 6 (1 point)

You work for a pharmaceutical company that is testing a new cholesterol drug. The proportion of patients on the previous drug who had a positive treatment was 0.414. You want to see if the new drug is more effective than the previous drug. You conduct a sample of 116 patients on the new drug and find that 81 have had a positive treatment effect. The 99% confidence interval is ( 0.5885 , 0.8081 ). What is the best conclusion you can make of those listed below?

Correct Answer:

3)We can claim that the proportion of patients who see a positive treatment effect with the new drug is larger than 0.414.

Reason : Since the confidence Interval is greater than 0.414 thus we can certainly conclude that the new drug has a positive effect on a larger proportion of patients.

Question 7 (1 point)

In a packing plant, one of the machines packs jars into a box. A sales rep for a packing machine manufacturer comes into the plant saying that a new machine he is selling will pack the jars faster than the old machine. To test this claim, each machine is timed for how long it takes to pack 10 cartons of jars at randomly chosen times. Given a 95% confidence interval of (-8.73, -2.65) for the true difference in average times to pack the jars (old machine - new machine), what can you conclude from this interval?

Correct Answer:

5)We are 95% confident that the average packing time of the new machine is greater than the old machine. The sales rep does not appear to be telling the truth.

Reason: Since the Confidence Interval contains only negative value thus we can conclude that the true mean of differences is is negative which can only happen when the time taken by the new machine is greater than the old machine .

Question 8 (1 point)

Researchers in the corporate office of an airline wonder if there is a significant difference between the cost of a flight on Priceline.com vs. the airline's own website. A random sample of 20 flights were tracked on Priceline and the airline's website and the average difference between the vendors was $4.294 with a standard deviation of $5.3109. The 99% confidence paired-t interval for price (Priceline - Airline Site) was (0.8965, 7.6915). Which of the following is the appropriate interpretation?

5)	We are 99% confident that the average difference in price between the two vendors for all flights is between 0.8965 and 7.6915.

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