Question

class of 18 students.

(7, 13), (9, 7), (14, 14), (15, 15), (10, 15), (9, 7), (14, 11), (14, 15), (8, 10), (9, 10), (15, 9), (10, 11), (11, 14), (7, 14), (11, 10), (14, 11), (10, 15), (9, 6)

Create a scatter plot of the data. What kind of correlation does the data appear to have?

A. Positive correlation
B. Negative correlation
C. No correlation
D. None of the above

Answer: C

2. Use the regression feature of a graphing utility to find a linear model for the data below. Let t represent the year with t = 9 corresponding to 1999.

Year:|Avg length (L) in minutes:
1999|2.38
2000|2.56
2001|2.74
2002|2.73
2003|2.87
2004|3.05

Which of the following shows the equations of the least squares regression line?

A. L = 7.82t - 9.78
B. L = 7.82t - 17.78
C. L = 0.12t + 2.29
D. L = 0.12t + 1.32

Answer: C

3. Using the same graph presented in the previous question, find the least squares regression line of the data below using the regression feature of a graphing utility. Then, find the average lengths of cellular calls for the year 2013.

A. 242.88 minutes
B. 4.08 minutes
C. 3.48 minutes
D. 3.97 minutes

Answer: B

4. Using the same graph again, find the least squares regression line of the data below using the regression feature of a graphing utility. Then, find the correlation coefficient for the regression line. Round to four decimal places.

A. 0.9766
B. 0.9537
C. 0.971
D. 0.6547

Answer: C