Math 227 Elementary Statistics-Minitab Handout Ch10

$Math 227 Elementary Statistics-Minitab Handout Ch10$

Ch10.

In Question #1- #5

Construct the scatter diagram.
Find the value of the linear correlation coefficient r.
Determine whether there is a significant linear correlation between the two variables.
If there is a positive/negative linear correlation, find the equation of the regression line.
Find the best predicted value for a requested x.

#1Car Rental Companies: (Ch10 Section 10-1 Example 10-1) Open (or type) the data shown for car rental companies in the United States for a recent year.

#2. When bears were anesthetized, researchers measured the distances (in inches) around

their chests and they weighted the bears (in pounds). The results are given below for

eight male bears. Based on the results, does a bear’s weight seem to be related to its

chest size?

X Chest (in.) 26 45 54 49 41 49 44 19

Y Weight (lb.) 90 344 416 348 262 360 332 34

Find the best predicted weight of a bear with a chest size of 52 in.

#3The accompanying table lists weights (in hundreds of pounds) and highway fuel usage

rates (in mi./gal) for a sample of domestic new cars. Based on the result, can you expect

to pay more for gas if you buy a heavier car?

X Weight 29 35 28 44 25 43 30 33 28 24

Y Fuel 31 27 29 25 31 29 28 28 28 33

Find the best predicted fuel consumption amount for a car that weights 4200 lb.

(Note that the table has values of x given in hundreds of pounds)

#4The paired data below consist of weights (in pounds) of discarded paper and sizes of

households.

Paper 2.41 7.57 9.55 8.82 8.72 6.96 6.83 11.42

Household Size 2 3 3 6 4 2 1 5

What is the best predicted size of a household that discards 10.00 lb. of paper?

#5A study was conducted to investigate a relationship between age (in years) and BAC

(blood alcohol concentration) measured when convicted DWI jail inmates were first

arrested. Sample dates are given below for randomly selected subjects. Based on the

result, does the BAC level seem to be related to the age of the person tested?

Age 17.2 43.5 30.7 53.1 37.2 21.0 27.6 46.3

BAC 0.19 0.20 0.26 0.16 0.24 0.20 0.18 0.23

What is the best predicted blood alcohol level of a person 21.0 years of age who has been convicted and jailed for DWI? (The BAC level is measured when the person is first arrested.)

How to Do it:

Create a Scatter Plot

- Choose Graph > Scatterplot, then select Simple and click OK

- Double-click on an appropriate column for the “Y variables”

- Double-click on an appropriate column for the “X variables”

- Click Data View and choose Symbols for the Data Display. Click OK

- Click Label, type the label that you want it to be called, and click Ok twice

Calculate Correlation coefficient

- Choose Stat > Basic Statistics > Correlation

- Double-click the columns intended for the “Variables.” The box for Display p-values

should be checked.

- Click Ok

Find equation of the regression line

- Choose Stat > Regression > Regression

- Double-click the column intended for the “Response” variable Y.

- Double-click the column intended for the “Predictors” variable X.

- Click Ok

(Optional) Obtaining Residuals

- Choose Stat > Regression > Regression

- Click on Storage, then check the boxes for the Residuals and Fits.

- Click Ok twice

Computing Response Variable Estimates

- Choose Stat > Regression > Regression

- Double-click the column intended as the “Response” variable and the column

intendedfor the “Predictor” variable

- Click Options

- Type in value as the “Prediction intervals for new observations”

- Click Ok twice