Chapter Nine Test Review

Calculate the correlation coefficient, r, for the data below. 4/21

-0.104

Explain the difference between sigma x^2 and (sigma x)^2.

The first symbol means square each x-value and then add the squares, and the 2nd symbol means add the x-values and then square the sum.

For the data below, test the significance of the correlation coefficient using α = 0.10 and the claim o=0 -13/18 12/14

critical value t0 = ± 1.860; standardized test statistic t ≈ 0.296; fail to reject H0; There is not sufficient evidence to conclude that a significant correlation exists.

For the data below, test the significance of the correlation coefficient using a= 0.05 and the claim o=0

critical value t0 = ± 2.306; standardized test statistic t ≈ 19.85; reject H0; There is sufficient evidence to conclude that a significant correlation exists.

Given the length of a human's femur, x, and the length of a human's humerus, y, would you expect a positive correlation, a negative correlation, or no correlation?

positive correlation

The data below are the average monthly temperatures, in °F, and the monthly natural gas consumption, in ccf, for a household in northwestern Pennsylvania. Find the equation of the regression line for the given data. 47/34

y hat = -4.310x + 296.352

The data below are the average monthly temperatures, in °F, and the monthly natural gas consumption, in ccf, for a household in northwestern Pennsylvania. Calculate the correlation coefficient, r. 47/34

-0.909

The data below are the number of absences and the final grades of 9 randomly selected students from a statistics class. Calculate the correlation coefficient, r. 2/92

-0.991

Given the equation of a regression line is = 3.5x - 5.4, what is the best predicted value for y given x=-1.2 Assume that the variables x and y have a significant correlation.

-9.6

Calculate the correlation coefficient, r, for the data below. 4/-16

0.990

The data below are the final exam scores of 10 randomly selected statistics students and the number of hours they studied for the exam. What is the best predicted value for y given x=5 Assume that the variables x and y have a significant correlation. 3/65

81

Find the equation of the regression line for the given data. -5/11

= -0.206x + 2.097

A manager wishes to determine the relationship between the number of miles (in hundreds of miles) the manager's sales representatives travel per month and the amount of sales (in thousands of dollars) per month. Find the equation of the regression line for the given data.

= 3.529x + 37.916

The data below are the average monthly temperatures, in °F, and the monthly natural gas consumption, in ccf, for a household in northwestern Pennsylvania. What is the best-predicted value for the gas consumption, y, given x = 50°F? Assume that the variables x and y have a significant correlation. 47/34

About 81 ccf.

If Data A has a correlation coefficient of r = -0.991, and Data B has a correlation coefficient of r = 0.991, which correlation is correct?

Data A and Data B have the same strength in linear correlation.

An agricultural business wants to determine if the rainfall in inches can be used to predict the yield per acre on a wheat farm.

explanatory variable: rainfall in inches; response variable: yield per acre

In order for applicants to work for the foreign-service department, they must take a test in the language of the country where they plan to work. The data below show the relationship between the number of years that applicants have studied a particular language and the grades they received on the proficiency exam. Construct a scatter plot for the data. 3/61

graph on computer

The data below are the gestation periods, in months, of randomly selected animals and their corresponding life spans, in years. Construct a scatter plot for the data. Determine whether there is a positive linear correlation, a negative linear correlation, or no linear correlation. 8/30

graph on computer

The data below are the temperatures on randomly chosen days during a summer class and the number of absences on those days. Construct a scatter plot for the data. 72/3

graph on computer

Given the equation of a regression line is = -1.04x + 50.3, determine whether there is a positive linear correlation or a negative linear correlation.

negative linear correlation