Variables X and Y have r = 0.40. If we decrease each X value by 0.1, double each Y value, and then interchange them (put X on the Y- axis and vice versa) the new correlation will be
A) 0.15 B) 0.60 C) -0.40 D) 0.40 E) 0.80
Q. 2For families who live in apartments the correlation between the family's income and the amount of rent they pay is r = 0.60. Which is true?
I. In general, families with higher incomes pay more in rent.
II. On average, families spend 60 of their income on rent.
III. The regression line passes through 60 of the (income, rent) data points.
A) I, II, and III B) I only C) I and III only D) I and II only E) II only
Q. 3A lakeside restaurant found the correlation between the daily temperature and the number of meals they served to be 0.40.
On a day when the temperature is two standard deviations above the mean, the number of meals they should plan on serving is _?_ the mean.
A) 0.16 SD above
B) equal to
C) 0.8 SD above
D) 2.0 SD above
E) 0.4 SD above
Q. 4It takes a while for new factory workers to master a complex assembly process. During the first month new employees work,
the company tracks the number of days they have been on the job and the length of time it takes them to complete an assembly. The correlation is most likely to be
A) exactly -1.0 B) exactly +1.0 C) near +0.6 D) near 0 E) near -0.6
Q. 5Music and grades (True Story) A couple of years ago, a local newspaper published research results claiming a positive association between the number of years high school children had taken instrumental music lessons
and their performances in school (GPA).
a. What does positive association mean in this context?
b. A group of parents then went to the School Board demanding more funding for music programs as a way to improve student chances for academic success in high school. As a statistician, do you agree or disagree with their reasoning? Explain briefly.
Q. 6Education research consistently shows that students from wealthier families tend to have higher SAT scores.
The slope of the line that predicts SAT score from family income is 6.25 points per 1000, and the correlation between the variables is 0.48. Then the slope of the line that predicts family income from SAT score (in 1000 per point)
A) is 6.25 B) is 0.037 C) is 3.00 D) is 13.02 E) is 0.16
Q. 7A medical researcher finds that the more overweight a person is, the higher his pulse rate tends to be. In fact, the model suggests that 12-pound differences in weight are associated with differences in pulse rate of 4 beats per minute.
Which is true?
I. The correlation between pulse rate and weight is 0.33
II. If you lose 6 pounds, your pulse rate will slow down 2 beats per minute.
III. A positive residual means a person's pulse rate is higher than the model predicts.
A) none
B) I only
C) II and III only
D) III only
E) II only
Q. 8The correlation between a family's weekly income and the amount they spend on restaurant meals is found to be r = 0.30. Which must be true?
I. Families tend to spend about 30 of their incomes in restaurants.
II. In general, the higher the income, the more the family spends in restaurants.
III. The line of best fit passes through 30 of the (income, restaurant) data points.
A) II only
B) II and III only
C) I only
D) III only
E) I, II, and III
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