Question 6
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.
Part I) Which distribution should you use for for determining aconfidence interval for estimating the population mean for used carsales costs?
a  Normal Distribution
b    t Distribution
c    Uniform
d    Chi Sq distribution
Part II) What is the number of degrees of freedom (df) for thisproblem.
Par III) 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.
Part IV) Define the random variable X ¯ (Xbar) byselecting the appropriate 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.
Part V) Construct a 95% confidence interval for the populationmean time wasted.
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.
Part VI)
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.
