Question

Q4) A national air traffic control system handled an average of 47,665 flights during 29 randomly selected days in a recent year. The standard deviation for this sample is 6,208 flights per day. Complete parts a through c below.

a. Construct a 99​% confidence interval to estimate the average number of flights per day handled by the system.

The 99​% confidence interval to estimate the average number of flights per day handled by the system is from a lower limit of nothing to an upper limit of nothing.

​(Round to the nearest whole​ numbers.)

b. Suppose an airline company claimed that the national air traffic control system handles an average of​ 50,000 flights per day. Do the results from this sample validate the airline​company's claim?

A.Since the 99​% confidence interval does not contain​ 50,000, it can be said with 99​% confidence that the sample validates the airline​ company's claim.

B.Since the 99​% confidence interval does not contain​ 50,000, it cannot be said with 99​% confidence that the sample validates the airline​ company's claim.

C.Since the 99​% confidence interval contains​ 50,000, it can be said with 99​% confidence that the sample validates the airline​company's claim.

D.Since the 99​% confidence interval contains​ 50,000, it cannot be said with 99​% confidence that the sample validates the airline​company's claim.

c. What assumptions need to be made about this​ population?

A.Since the sample size is not greater than or equal to​ 30, one needs to assume that the population distribution is not very skewed to one side.

B.Since the sample size is not greater than or equal to​ 30, one needs to assume that the population follows the normal probability distribution.

C.Since the sample size is not greater than or equal to​ 30, one needs to assume that the population follows the​ Student's t-distribution.

D.Since the sample size is not greater than or equal to​ 30, one needs to assume that the population distribution is skewed to one side.

a. The 95​% confidence interval has a lower limit of ​$ and an upper limit of $.

​(Round to the nearest cent as​ needed.)

b. The margin of error is $ .

​ (Round to the nearest cent as​ needed.)

Q5)  A​ country's tax collection agency reported that 86​% of individual tax returns were filed electronically in 2017. A random sample of 237 tax returns from 2018 was selected. From this​sample, 197 were filed electronically. Complete parts a through c.

a. Construct a 95​% confidence interval to estimate the actual proportion of taxpayers who filed electronically in 2018.

The confidence interval has a lower limit of nothing and an upper limit of nothing.

​(Round to three decimal places as​ needed.)

b. What is the margin of error for this​ sample?

The margin of error is nothing.

​(Round to three decimal places as​ needed.)

c. Is there any evidence that this proportion has changed since 2017 based on this​ sample? This sample

▼ provides does not provide evidence that this proportion has changed since 2017​,

since the ▼

Q6) Determine the sample size n needed to construct a 95​% confidence interval to estimate the population mean when σ=36 and the margin of error equals 6.

N=

Q7)  Determine the sample size n needed to construct a 90​% confidence interval to estimate the population proportion when p=0.39 and the margin of error equals 8​%.

n=

​(Round up to the nearest​ integer.)

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Answer 1