Question

You are the VP at a car dealership. Your boss comes to you one afternoon and asks if you could tell him the average profit per vehicle the dealership makes. He wants the information by the end of the day. Sounds easy enough except that each salesman keeps track of their average profit per vehicle and only 20 salesmen of the 40 employed work at the dealership on a given day. You collect the information below from the salesmen currently on shift. You want to give your boss an answer you are 95% confident in. What do you tell him?

Average Profit per Vehicle
$ 5,125.00	$ 1,850.00	$ 4,620.00	$ 3,448.00	$ 2,158.00
$ 2,689.00	$ 4,896.00	$ 6,411.00	$ 5,128.00	$ 4,169.00
$ 1,689.00	$ 4,855.00	$ 2,177.00	$ 3,891.00	$ 4,588.00
$ 3,485.00	$ 3,489.00	$ 2,488.00	$ 4,812.00	$ 2,588.00

Question 1:

Calculate the lower and upper confidence limit based on this information.

Enter in the name of the data points you need to solve this.

Lower Bound
Upper Bound

Question 2:

Based on your findings above, what will you tell your boss the average profit is at the company?

The next day your boss comes to you and says he reviewed the statement you made and asks if you are sure about your answer. It just so happens the other 20 salesmen were at work that day and you are able to gather the remaining data points. What do you tell your boss?

Average Profit per Vehicle
$ 5,125.00	$ 1,850.00	$ 4,620.00	$ 3,448.00	$ 2,158.00
$ 2,689.00	$ 4,896.00	$ 6,411.00	$ 5,128.00	$ 4,169.00
$ 1,689.00	$ 4,855.00	$ 2,177.00	$ 3,891.00	$ 4,588.00
$ 3,485.00	$ 3,489.00	$ 2,488.00	$ 4,812.00	$ 2,588.00
$ 4,258.00	$ 3,155.00	$ 3,892.00	$ 2,988.00	$ 3,500.00
$ 2,458.00	$ 5,348.00	$ 4,122.00	$ 5,841.00	$ 3,678.00
$ 1,244.00	$ 5,133.00	$ 2,645.00	$ 4,722.00	$ 2,841.00
$ 1,879.00	$ 3,610.00	$ 5,179.00	$ 3,615.00	$ 2,130.00

Question 3:

Calculate the lower and upper confidence limit based on this information.

Enter in the name of the data points you need to solve this.

Lower Bound
Upper Bound

Question 4:

Based on your findings above, what will you tell your boss the average profit is at the company?

Answer 1

using minitab>stat>basic stat>one sample t

we have

One-Sample T: data

Variable N Mean StDev SE Mean 95% CI
data 20 3728 1325 296 (3108, 4348)

Ans `1 )

Lower bound = 3108

upper bound = 4348

Ans 2 ) we will tell that we are 95 % confident that the average profit per vehicle for all the dealership makes.is lies in between (3108,4348)
Ans 3 )

using minitab>stat>basic stat>one sample t

we have

Variable N Mean StDev SE Mean 95% CI

data 40 3670 1266 200 (3265, 4075)

Lower bound = 3265

upper bound = 4075

Ans 4) we will tell that we are 95 % confident that the average profit per vehicle for all the dealership makes.is lies in between (3265,4075)