6. The ages in years that 7 girls and 7 boys learned to ride a bicycle are listed below. Is there sufficient evidence to conclude that the mean ages for the two sexes differ?

Girls Boys

4.8 4.9

4.1 4.8

5.2 5.6

4.9 5.5

5.1 4.1

5.3 4.5

5.7 5.8

7. A researcher believes that she has designed a keyboard that is more comfortable to use than a standard keyboard. In order to help decide if this is the case, typing speeds were taken for 8 different people on each keyboard. The lengths of time, in minutes, for each of the people to type a pre-selected manuscript are listed below. Assume the two populations are normal. Use the data to determine if there is a significant difference in time for the two keyboards. Use .05 significance level.

Person Original New

1 15 12

2 9 8

3 17 15

4 10 8

5 9 5

6 4 4

7 30 25

8 29 21

13. A librarian has collected the following data, where x = carts of books to shelve and y = the time it takes to shelve them.

x y

4 1.0

8 2.0

10 2.5

13 6.0

16 8.0

11 3.5

5 1.3

9 2.5

18 9.0

14 6.0

6 1.4

12 5.0

20 10.5

1. Construct a scatter diagram
2. Estimate the linear regression equation E(y) = [alpha] +[beta]x
3. How much of the variation in y is explained by its linear relationship with x?
4. Test H0: [beta] = 0 against Ha: [beta] does not = 0. Report the value of the test statistic, the df , the P-value, and interpret the results.
5. Construct a 95% confidence interval for [beta] and interpret.

15. We are interested in studying the systolic blood pressure Y in relation to weight X1 and age X2 in a class of males approximately the same height. Data from 13 randomly selected subjects are given below.

Subject Weight X1 Age X1 Blood Pressure Y

1 152 50 120

2 183 20 141

3 171 20 124

4 165 30 126

5 158 30 117

6 161 50 129

7 149 60 123

8 158 50 125

9 170 40 132

10 153 55 123

11 164 40 132

12 190 40 155

13 185 20 147

1. Fit a multiple regression model to this data and report the prediction equation.
2. Find the predicted systolic blood pressure for the first subject. Find the residual and interpret.
3. Report R-squared and the multiple correlation and interpret.

Price: $15.71

Solution: The downloadable solution consists of 8 pages, 771 words and 10 charts.
Deliverable: Word Document