2. Two variables have a positive linear correlation. Is the slope of the regression line for the variables positive or negative?

[DATA] Concrete As concrete cures, it gains strength. The following data represent the 7-day and 28-day strength (in pounds per square inch) of a certain type of concrete:

d. Assuming the residuals are normally distributed, test whether a linear relation exists between 7-day strength and 28-day strength at the alpha = 0.05 level of significance

The scatterplot below shows a set of data and its least-squares regression line. Based on the graph, which of the following is most likely the equation of the regression line?

A regional sales manager records data on the number of clients a salesperson contacts in a week (x) and the total sales generated that week (y). The data from 10 salespeople is shown below. Find the equation of the regression line and use it to predict sales if the salesperson contacts (a) 6 clients; (b) 40 clients

"In Exercises 9 and 10, identify the explanatory variable and the response variable.

9. A nutritionist wants to determine whether the amounts of water consumed each day by persons of the same weight and on the same diet can be used to predict individual weight

loss."

5. To predict y-values using the equation of a regression line, what must be true about the correlation coefficient of the variables?

"In Exercises 7-12, match the description in the left column with its symbol(s) in the right column.

7. The y-value of a data point corresponding to x;

a. \hat{y}_i

b. y_i

c. b

d. (\bar{x}, \bar{y})

e. m

f. \bar{y}"

"In Exercises 7-12, match the description in the left column with its symbol(s) in the right column.

9. Slope

a. \hat{y}_i

b. y_i

c. b

d. (\bar{x}, \bar{y})

e. m

f. \bar{y}"

"In Exercises 7-12, match the description in the left column with its symbol(s) in the right column.

12. The point a regression line always passes through

a. \hat{y}_i

b. y_i

c. b

d. (\bar{x}, \bar{y})

e. m

f. \bar{y}"