Stat, Ch 3 Review

The height (in feet) and volume (in cubic feet) of usable lumber of 32 cherry trees are measured by a researcher.

In this study, the response variable is...

• height of researcher.

• volume of lumber.

• height of tree.

• impossible to determine.

Which of the following statements are supported by the scatterplot?

I. There is a positive association between height and volume.

II. There is an outlier in the plot.

III. As the height of a cherry tree increases, the volume of useable lumber it yields increases.

• I, II, and III

• I only

• II only

• I and II only

If the data point (65,70) were removed from this study, how would the value of the correlation r change?

• r would not change, since it’s value does not depend which variable is used for x and which is used for y.

• r would be smaller, because this point falls in the pattern of the rest of the data.

• r would be larger, since this point does not fall in the pattern of the rest of the data.

• r would be smaller, since there are fewer data points.

A study is conducted to determine if one can predict the yield of a crop based on the amount of fertilizer applied to the soil.

The response variable in this study is...

• amount of fertilizer applied to the soil.

• the experimenter.

• amount of rainfall.

• yield of the crop.

Two variables are said to be negatively associated if...

• larger values of one variable are associated with larger values of the other.
  
• larger values of one variable are associated with smaller values of the other.
  
• smaller values of one variable are associated with smaller values of the other.
  
• smaller values of one variable are associated with both larger or smaller values of the other.
  

You would draw a scatterplot to...

• show the distribution of heights of students in this course.
• show the relationship between gender and having a driver’s license.
• compare the distributions of heights for male and female students in this course.
• show the relationship between the height of female students and the heights of their mothers.

The correlation coefficient measures...

• whether there is a relationship between two variables.
  
• the strength of the relationship between two quantitative variables.
  
• whether a cause and effect relation exists between two variables.
  
• the strength of the linear relationship between two quantitative variables.
  

Which of the following are most likely to be negatively correlated?

• The percentage of body fat and the time it takes to run a mile for male college students.
  
• The heights and yearly earnings of 35-year-old U.S. adults.
  
• Gender and yearly earnings among 35-year-old U.S. adults.
  
• The prices and the weights of all racing bicycles sold last year in Chicago.
  

The intercept of the least-squares regression line is approximately...

• –0.1.

• 1.8.

• 2.0

• 18

Based on the scatterplot, the least-squares line would predict that a car that emits 10 grams of CO per mile driven would emit approximately how many grams of NOX per mile driven?

• 1.7

• 2.2

• 1.1

• 0.7