Answer:
99% confidence interval for the true mean resale value of a 5-year-old car of this model is [$12,173.24 , $13,306.76].
Step-by-step explanation:
We are given that you manage to obtain data on 17 recently resold 5-year-old foreign sedans of the same model.
These 17 cars were resold at an average price of $ 12 comma 740 with a standard deviation of $ 800.
Firstly, the pivotal quantity for 99% confidence interval for the true mean is given by;
P.Q. =
~ 
where,
= sample average price = $12,740
s = sample standard deviation = $800
n = sample of cars = 17
= true population mean
<em>Here for constructing 99% confidence interval we have used One-sample t test statistics as we don't know about population standard deviation.</em>
<u>So, 99% confidence interval for the population mean, </u>
<u> is ;</u>
P(-2.921 <
< 2.921) = 0.99 {As the critical value of t at 16 degree of
freedom are -2.921 & 2.921 with P = 0.5%}
P(-2.921 <
< 2.921) = 0.99
P(
<
<
) = 0.99
P(
<
<
) = 0.99
<u>99% confidence interval for</u>
= [
,
]
= [
,
]
= [$12,173.24 , $13,306.76]
Therefore, 99% confidence interval for the true mean resale value of a 5-year-old car of this model is [$12,173.24 , $13,306.76].