1.In a recent sample of 84 used car sales costs, the sample meanwas $6,425 with a sample standard deviation of $3,156.

Assume the underlying distribution is approximately normal.

Which distribution should you use for for determining aconfidence interval for estimating the population mean for used carsales costs?

What is the number of degrees of freedom (df) for thisproblem.

Answer this question by:

Select the correct distribution and enter the appropriateletter.

Enter the degrees of freedom (df) for this problem. If this isan inappropriate question for the distribution being used enter thenumber 0

a   Normal Distribution

b     t Distribution

c     Uniform

d     Chi Sq distribution

Enter the answers for the 2 questions being asked in the sameorder in which they were asked.

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Define the random variable X by selecting theappropriate letter below.

a     An individual data item randomlyselected from the population, some times referred to as the parentpopulation.

b     The average of n individual data itemrandomly selected from the parent population. In this question n is84.

Define the random variable X ¯ (Xbar) by selecting theappropriate letter below.

c     An individual data item randomlyselected from the population, sometimes referred to as the parentpopulation.

d     The average of n individual data itemrandomly selected from the parent population. In this question n is84.

Enter your answers in the order in which the questions wereasked.

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Construct a 95% confidence interval for the population mean timewasted.

Enter your answers rounded to 0 decimal places (Enter answer asan integer).

In the two answer locations provided enter the lower bound ofthe confidence interval first followed by the upper bound.

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What is meant by the term “95% confident” when constructing aconfidence interval for a mean?

a.    If we took repeated samples, approximately95% of the samples would produce the same confidence interval.

b     If we took repeated samples,approximately 95% of the confidence intervals calculated from thosesamples would contain the sample mean.

c     If we took repeated samples, the samplemean would equal the population mean in approximately 95% of thesamples

d     If we took repeated samples, approximately95% of the confidence intervals calculated from those samples wouldcontain the true value of the population mean..

Enter the correct answer by selecting the appropriate letter

2.

The owner of the Britten's Egg Farm wants to estimate the meannumber of eggs produced per chicken.  A representativerandom sample of 25 chickens show they produce an average of 20eggs per month with a sample standard deviation (s) of 2 eggs permonth. The distribution is known to be symmetrical and is closeenough to normal to be treated as a normal distribution.

Answer the following questions related to the above paragraphand calculate a 90% confidence interval for the mean number of eggsproduced per chicken on the Britten's Egg Farm.

a     What is the point estimate of the meannumber of eggs produced per chicken?
       Enter answer with 0 decimalplaces (integer).

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b     What is the appropriate distribution forcalculating a 90% confidence interval?

a     Uniform distribution

b     Normal distribution

c     t distribution

d     Chi Square distribution

Answer this question by entering the appropriate letter.

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c     The degrees of freedom (df) for thisproblem is?
       Enter Na or 0 for the df ifthe appropriate distribution does not required a df.

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e     The 90% conference interval for themean number eggs produced per month is:

Enter the lower and upper limits for the conference interval byentering the lower limit first.
Rounded each conference limit to 1 decimal point.

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F     Prior to this study the owner of theBritten's Egg Farm Egg Farm believed the mean amount off eggsproduced per month on his farm was 22.

Does the study support his belief with a 90% confidence?

a     Yes. The mean amount of eggs producedper month on his farm could be 22 per month because the number 22is not contained in the confidence interval.

b     Yes. The mean amount of eggsproduced per month on his farm could be 22 per month because thenumber 22 is contained in the confidence interval.

c     No. The mean amount of eggsproduced per month on his farm is most likely not 22 per monthbecause the number 22 is not contained in the confidenceinterval.

d     No. The mean amount of eggs producedper month on his farm is most likely not 22 per month because thenumber 22 is contained in the confidence interval.

e    The owner can not comment on the mean amountof eggs produced per month on his farm because the confidenceinterval is based upon a sample.

Enter the correct answer by selecting and entering theappropriate letter.

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