Question

Question 5 (1 point)

You are interested in getting an investment portfolio started with any extra money you make from your part time job while also going to school. While flipping through the latest edition of Money magazine, you read an article that of a survey of magazine subscribers, 194 were randomly selected and analyzed. A 95% confidence interval was constructed for the proportion of all subscribers who made money in the previous year in their investments, which was ( 0.777 , 0.8828 ). What is the correct interpretation of this confidence interval?

Question 5 options:

1)	We are certain that 95% of subscribers made between 0.777 and 0.8828.

2)	We cannot determine the proper interpretation of this interval.

3)	We are 95% confident that the proportion of all Money magazine subscribers that made money in the previous year from their investments is between 0.777 and 0.8828.

4)	We are 95% confident that the proportion of all Money magazine subscribers sampled that made money in the previous year from their investments is between 0.777 and 0.8828.

5)	We are 95% confident that of the 194 respondents, between 0.777 and 0.8828 of them made more than they lost.

Question 6 (1 point)

Suppose you want to determine the average height of college basketball players in NCAA Division I. In a random sample of 12 players, the sample average is 73.608 inches with a standard deviation of 5.7866 inches. What is the 95% confidence interval for the average height of all NCAA D-I players?

Question 6 options:

1)	( 69.931 , 77.285 )

2)	( 71.407 , 75.809 )

3)	( -69.931 , 77.285 )

4)	( 71.938 , 75.278 )

5)	( 69.968 , 77.248 )

Question 7 (1 point)

Suppose that you are the director of table game operations at a large casino, known especially for its poker room. You are interested in determining the average number of hands the casino should expect per hour during peak hours in the poker room. You monitor the number of hands over the next week and given a random sample of 22 hours, you see that on average 178.3 hands are played per hour, with a standard deviation of 9.78 hands and you calculated a 99% confidence interval to be (172.4, 184.2). Your manager believes the true mean is 141.7. Which of the following is the best conclusion?

Question 7 options:

1)	The average number of hands played per hour is not significantly different from 141.7

2)	The percentage of hours in which more than 141.7 hands of poker are played is 99%.

3)	We cannot determine the proper interpretation based on the information given.

4)	We are 99% confident that the average number of hands played per hour is greater than 141.7.

5)	We are 99% confident that the average number of hands played per hour is less than 141.7.

Question 8 (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 90% confidence interval of (-0.51, 6.95) for the true difference in average times to pack the jars (old machine - new machine), what can you conclude from this interval?

Question 8 options:

1)	We are 90% 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.

2)	We are 90% confident that the average packing time of the old machine is greater than the new machine. The sales rep appears to be correct.

3)	We are 90% confident that the difference between the two sample means falls within the interval.

4)	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.

5)	We do not have enough information to make a conclusion.

Answer 1

5)

We are 95% confident that the proportion of all Money magazine subscribers that made money in the previous year from their investments is between 0.777 and 0.8828.

6)

sample mean 'x̄=	73.608
sample size   n=	12.00
sample std deviation s=	5.787
std error 'sx=s/√n=	1.6704

for 95% CI; and 11 df, value of t=		2.201
margin of error E=t*std error    =		3.677
lower bound=sample mean-E =		69.931
Upper bound=sample mean+E =		77.285

option 1 is correct

7)

since interval values are all above 141.7:

We are 99% confident that the average number of hands played per hour is greater than 141.7

8)

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.