STAT 101: Chapter 6 HW

Graph B

-0.35

Graph C

-0.92

For the four scatterplots below, match the values of the correlation coefficient to the appropriate plot. scat1.jpg

...

Which of the following is a possible value for the correlation coefficient r?

0.43

Graph A

0.52

Graph D

0.98

In many cities, researchers have found a strong positive linear relationship between ice cream sales and the crime rate. Choose the most appropriate conclusion for this result.

Ice cream sales and the crime rate are associated, but changing ice cream sales will not change the crime rate.

Researchers were interested in determining the association between temperature (in degrees Fahrenheit) and percentage of elongation a sample of mozzarella cheese reaches before it rips. They take 7 samples and compute r = -0.1198. Suppose they want to change the temperature data to degrees Celsius. How will this change affect the correlation coefficient?

It will have no effect, r = -0.1198.

Studies have shown there is a positive relationship between reading skills and shoe size for elementary school-aged children. Choose the most appropriate conclusion for this result.

Older students have better reading skills and larger shoe sizes than younger students.

An introductory statistics student calculates the correlation coefficient between two quantitative variables to be r = 0. What does this tell you about the relationship between the two variables?

The two variables have no linear relationship to each other.

Data were collected on the city gas mileage and weight of 57 cars sold in the United States in 2004. The scatterplot is pictured below. The correlation between the two variables is -0.8781. cars2.jpg Choose the best description of the relationship between the two variables.

There is a fairly strong negative linear relationship between the city gas mileage and weight of the 57 cars. In general, cars that weigh more tend to have lower city gas mileage.

Data were collected on the girth (diameter in inches) and volume (in cubic feet) for 31 felled black cherry trees. The scatterplot is pictured below. The correlation between the two variables is 0.9671. trees.jpg Choose the best description of the relationship between the two variables.

There is a strong positive linear relationship between the girth and volume of these black cherry trees. Trees with higher girth have higher volume.

In a recent Consumer Reports article, mileage in 9 common car types was measured and compared to the tests run by the Environmental Protection Agency. The correlation between the EPA mileage and the CR mileage is r = 0.9839. Which statement correctly describes the relationship between the two variables?

There is a very strong positive correlation between the EPA mileage and the CR mileage.

Choose the correct words to describe the scatterplot below: moderatenegative.jpg The form of the relationship is linear . The strength of the relationship is moderate . The direction of the relationship is negative . There are no outliers.

linear moderate negative

Choose the correct words to describe the scatterplot below: weaknegative.jpg The form of the relationship is linear . The strength of the relationship is moderate . The direction of the relationship is negative . There are no outliers.

linear moderate negative

Choose the correct words to describe the scatterplot below: strongpositive.jpg The form of the relationship is linear . The strength of the relationship is strong . The direction of the relationship is negative . There are no outliers.

linear strong positive

Choose the correct words to describe the scatterplot below: nonlinearincreasing.jpg The form of the relationship is non-linear . The strength of the relationship is strong . The direction of the relationship is positive . There are no outliers.

non-linear strong positive

Chicken sandwiches are often advertised as a healthier alternative to hamburgers, since chicken is generally lower in fat than beef. Tests on 11 brands of fast-food chicken sandwiches were conducted and the grams of fat as well as number of calories were recorded for each sandwich. The correlation coefficient between the two variables was r = 0.947. The appropriate way to report this value is:

r = 0.947 (no units)