AP Stats: Midterm Review Exam Complete Questions And Correct Detailed Answers.
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Course
33401
Institution
33401
D - correct answer A forester studying oak trees finds that the correlation between x= the age (measured in years) and y= height (in feet) of a sample of trees is 0.78. Which of the following statements must be true?
a) 78% of the variability in tree heights ca...
D - correct answer A forester studying oak trees finds that the correlation between
x= the age (measured in years) and y= height (in feet) of a sample of trees is 0.78. Which of the following
statements must be true?
a) 78% of the variability in tree heights can be explained by variation on the trees' ages.
b) for every year a tree ages, its height increases on average by 78%.
c) if we let x= height of trees and y= age of trees, then the correlation would be the reciprocal of 0.78.
d) if we measure the height in meters instead of feet, the correlation would still be 0.78.
e) the unit for correlation in this context is foot-years.
D - correct answer One flight---Philadelphia to West Palm Beach, FL ---is 953 miles
long and costs $110. Which of the following expressions correctly represents the residual for this data
point?
a) 101.24+0.02977 * 953
b) 953-(101.24+ 0.02977 * 110)
c) (101.24 + 0.02977 * 110) - 953
d) 110- (101.24 + 0.02977 * 953)
e) (101.24 + 0.02977 * 953) - 110
C - correct answer Which of the following best describes what S=20.7237
measures?
a) the standard deviation of air fares
b) the standard deviation of flight distances
c) the standard deviation of the residuals
d) the slope of the least squares regression line
e) the standard deviation of the slope
, A - correct answer The unusual point in the upper left part of the plot is for navy
beans, with 15.8 grams of protein and 15.8 grams of carbohydrates. Which of the following best
describes how correlation would change if we removed navy beans from the data set?
a) the correlation would be closer to 1, because the remaining data would have a stronger positive
relationship.
b) the correlation would be closer to 1, because there would be fewer individuals in the data set.
c) the correlation would be closer to 0, because the data would more closely resemble a straight line.
d) the correlation would be closer to 0, because the standard deviation of the residuals would be
smaller.
e) correlation would no longer be calculated, because the remaining data would fall into two distinct
groups.
A - correct answer The protein content for the 15 bean varieties has a mean of 12.2
grams and a standard deviation of 5.3 grams. The mean carbohydrate content is 33.6 grams with a
standard deviation of 15.7 grams. The correlation is 0.84. Which of the following expressions represents
the slope of the least squares regression of y= protein content on x= carbohydrate content?
a) (0.84)(5.3)/(15.7)
b) (0.84)(15.7)/(5.3)
c) (0.84)(12.2)/(33.6)
d) (0.84)(33.6)/(12.2)
e) (33.6)/(0.84)(12.2)
C - correct answer The least squares regression line minimizes which of the
following quantities?
a) the sum of the squared differences between the observed values of the response variable and the
mean of the response variable
b) the sum of the squared differences between the observed values of the explanatory variable and the
mean of the explanatory variable
c) the sum of the squared differences between the observed values of the response variable and the
predicted values of the response variable
d) the sum of the squared differences between the observed values of the explanatory variable and the
predicted values of the explanatory variable
e) the sum of the squared differences between the predicted values of the explanatory variable and the
mean of the explanatory variable
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