Statistic homeword help

[RoseNJ]

I got 9 answers from the question below, but I wasn't sure, there was right answer, please someone give me idea?

1) A local eat-in pizza restaurant wants to investigate the possilility of starting to deliver pizzas. The owner of the store has determined that home delivery will be successful if the average time spent on the deliveries does not exceed 35 minutes. The owner has randomly selected 24 customers and has delivered pizzas to their homes. The owner of the store views the delivery possibility as a method of expanding her business. She is concerned with the possibility of incorrectly concluding that the mean delivery time exceeds 35 minutes, when, in fact, the mean really equals 35 minues. In terms of our error, she is concerved with making________error.

A) a Type I
B) a Type III
C) both a Type I and Type II
D) a Type II

2) A local eat-in pizza restaurant wants to investigate the possilility of starting to deliver pizzas. The owner of the store has determined that home delivery will be successful if the average time spent on the deliveries does not exceed 27 minutes. The owner has randomly selected 20 customers and has delivered pizzas to their homes. The owner of the store views the delivery possibility as a method of expanding her business. She is concerned with the possibility of incorrectly concluding that the mean delivery time exceeds 27 minutes, when, in fact, the mean really equals 27 minues. In terms of our error, she is concerved with making________error.

A) a Type I
B) both a Type I and Type II
C) a Type III
D) a Type II

3) A radio station claims that the amount of advertising per hour of broadcast time has an average of 13 minutes and a standard deviation equal to 1.4 minutes. You listen to the radio station for 1 hour, at a randomly selected time, and carefully observe that the amount of advertising time is equal to 7 minutes. Calculate the z-score for this amount of advertising time.

A) z = - 8.4
B) 4.29
C) z = - 4.29
D) z = 0.43

4) Forty-five CEOs from the electronics industry were randomly sampled and a 99% confidence interval for the average salary of all electronics CEOs was constructed. The interval was ($121,745, $132,249). At what level of reliability are the inferences derived from this information valid?

A) 0.99%
B) 1%
C) 49.5%
D) 99%

5) Forty-five CEOs from the electronics industry were randomly sampled and a 90% confidence interval for the average salary of all electronics CEOs was constructed. The interval was ($120,158, $138,149). To make more useful inferences from the data, it is desired to reduce the width of the confidence interval. Which of the following will result in a reduced interval width?

A) Increase the sample size and increase the confidence level.
B) Decrease the sample size and increase the confidence level.
C) Increase the sample size and decrease the confidence level.
D) Decrease the sample size and decrease the confidence leve.

6)) A marketing research company needs to estimate the average total compensation of CEOs in the service industry. Data were randomly collected from 18 CEOs and the 97% confidence interval was calculated to be ($2,181,260, $5,836,180). Explain what the phrase "97% confident" means.

A) 97% of the similarly constructed intervals would contain the value of the sample mean.
B) The probability that the population mean falls in any confidence interval constructed is .97%.
C) 97% of the population values will fall in the interval.
D) In repeated sampling, 97% of the intervals constructed would contin u.

7) The Central Limit Theorem says the sampling distribution of the sample mean is approximetely normal under certain conditions. Which of the following is a necessary condition for the Central Limit Theorem to be used?

A) The sample size must be large (e.g., at least 30).
B) The population from which we are sampling must not be normally distributed.
C) The population size must be large (e.g., at least 30).
D) The population from which we are sampling must be normally distributed.

8) The Central Limit Theorem is important in statistics because ___________

A) for a large n, it says the population is approximately normal
B) for any population, it says the sampling distribution of the sample mean is approximately normal, regardless of the sample size
C) for any size sample, it says the sampling distribution of the sample mean is approximately normal
D) for a large n, it says the sampling distribution of the sample mean is approximately normal, regradless of the population.

9) The Central Limit Theorem is considered powerful in statistics because ___________

A) It works for any sample size provided the population is normal
B) It works for any sample provided the population distribution is known
C) It works for any population distribution provided the sample size is sufficiently large
D) It works for any population distribution provided the population mean is known.

[noble]

if the z-score is normalized random variable then #3's answer is
C.

As far as the other questions go, I'm confident with your answers
for 7

Also, I believe
#8 should be D
#9 should be C

The central limit theorem basically says that the more you
samples you add, the closer the mean gets to a value.
Hence, central limit.

[RoseNJ]

thank noble

[noble]

anytime, glad i can help

[RoseNJ]

How about another questions ? do you think I get right answers ?

[noble]

i dont know about the other questions it's been a while since i had probability/statistics

the only things that i know regarding your hw is the probability
side because i still use it in practice

[Vindictive]

ok then.

[DavidHooper]

Also, I believe
#8 should be D
#9 should be C

Yup, agreed.

1) isn't C). And it isn't B). It's A) or D) - haven't done Type I or II errors for ages.

2) is the same as whatever 1) is.

I think 3) is B) or C).

5) is A).


RoseNJ = Vindictive ?