AP Stats Chapter 3 Review

A least-squares regression line for predicting performance on a college entrance exam based on high school grade point average (GPA) is determined to be
predicted score = 273.5 + 91.2(GPA)
One student in the study had a high school GPA of 3.2 and an exam score of 550.  What is the residual for this student? 

• 15.34

• 40.23

• -40.23

• -15.34

The correlation coefficient measures

• whether there is a relationship between two variables

• the strength of the relationship between two quantitative variables

• whether or not a scatterplot shows an interesting pattern

• the strength of the linear relationship between two quantitative variables

What kind of correlation?

• Weak Positive

• Weak Negative

• Strong Positive

• Strong Negative

The fraction of the variation in the values of y that is explained by the least-squares regression of y on x is

• the correlation

• the slope of the least-squares regression line

• the square of the correlation coefficient

• the intercept of the least-squares regression line

• the residual

Data is obtained for a large group of college students relating the time they spent writing an essay and the grade on the essay. The equation is grade = 30.18 + 6.49(time) with r = 0.724 What percentage of the variation in grades can be explained by looking at time spent on the essay?

• 52.4%

• 72.4%

• 27.6%

• 47.6%

select the true statement:

• the five number summary consists of the minimum, Q1, mean, Q3, and max values

• the IQR is a measure of spread and is found by adding the lower and upper quartiles

• if the shape of a distribution is skewed, then you should report the median and IQR instead of the mean and standard deviation when describing the distribution

• the median can be greatly affected by extreme values

Interpret the slope of the Least Squares Line Equation.

• Income increases by 31.45 with each additional 2 hours worked.

• Income increases by 31.45

• As hours increases by one, income will increase by 31.45.

• As hours increases by one, income will decrease by 242.3.

Which of the following is NOT a measure of spread?

• IQR

• Mean

• Standard Deviation

• Range

Gina's doctor told her that the standardized score (z- score) for her systolic blood pressure, as compared to the blood pressure of other women her age, is 1.50. Which of the following is the best interpretation of this standardized score?

• Gina's systolic blood pressure is 150.

• Gina's systolic blood pressure is 1.50 standard deviations above the average systolic blood pressure of women her age.

• Gina's systolic blood pressure is 1.50 above the average systolic blood pressure of women her age.

• Gina's systolic blood pressure is 1.50 times the average systolic blood pressure for women her age.

• Only 1.5% of women Gina's age have a higher systolic blood pressure than she does.

A company wanted to determine the health care costs of its employees. A sample of 25 employees were interviewed and their medical expenses for the previous year were determined. Later the company discovered that the highest medical expense in the sample was mistakenly recorded as 10 times the actual amount. However, after correcting the error, the corrected amount was still greater than or equal to any other medical expense in the sample. Which of the following sample statistics must have remained the same after the correction was made?

• Mean

• Median

• Mode

• Range

• Variance