In a recent sample of 84 used car sales costs, the sample mean was $6,425 with a standard deviation of $3,156. Assume the underlying distribution is...

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

the underlying distribution is approximately normal.

a.

Which distribution should you use for this problem? Explain your choice.

b.

Define the random variable

X

̄

in words.

c.

Construct a 95% confidence interval for the population mean cost of a used car.

i.

State the confidence interval.

ii.

Sketch the graph.

iii.

Calculate the error bound.

d.

Explain what a “95% confidence interval” means for this study.