2. You randomly select 16 cars of the same model that were soldat a car dealership and determine the number of days each car saton the dealership’s lot before it was sold. The sample mean is 9.15days, with a sample standard deviation of 1.6 days. Construct a 95%confidence interval for the population mean number of days the carmodel sits on the dealership’s lot. (10 p)
(Round off final answers to two decimal places, if appropriate.Do not round off numbers taken directly from tables).
3. A researcher collected data from a random sample of 25 highschool freshmen and found the mean of the sample to be 85.40 on theTest of Critical Thinking (TCT). She also calculated the standarddeviation from the sample and discovered the value was 12.30. Theaverage score on the Test of Critical Thinking for all high schoolseniors in a large school district is 90.00. The researcher wantsto know if the mean TCT of the 25 high school freshmen in therandom sample is different from the population’s (i.e., highschoolseniors) TCT mean.
(Round off final answers to two decimal places, if appropriate.Do not round off numbers taken directly from tables).
e. What decision should be made about the null hypothesis? Inother words, should you reject or retain the null hypothesis?(10p)
g. Provide a brief conclusion regarding your findings. Use yourpower point lecture slides for writing out the interpretation ofyour results. (10p)
