Chapter 10 Review, Page 176, # 2 - 10 all



Chapter 10 Review, Page 176, # 2 - 10 all

2. (a) [pic] = (1)(0.8)(15) + 100 = 12 + 100 = 112 points.

b) Same as (a): 112 points

3. You could use the same method as in #2, but since there is several questions, the equation of the regression line might work better. Equation: Predicted wife height = [pic](husband’s height) + b (63 = (0.23)(68) + b. So b = 47, and the equation is: Wife’s height = 0.23 (Husband’s height) + 47.

d) Husband of 72”: wife = 0.23 (72) + 47; wife is 63.56 or about 64 inches tall

e) Husband of 64”: wife = 0.23(64) + 47; wife is 61.72 or about 62 inches tall

f) Husband of average height (68”), so predict the wife of average height = 63 inches

g) Husband unknown height; predict the average for the wife = 63 inches

4. a) [pic])(0.5)(3) + 12 = 15 years education

e) [pic])(0.5)(3) + 12 = 1.5 + 12 = 13.5 years education

f) It’s just the regression affect. If either (a) or (b) would have been below average, the answer would have been higher—above the spouse.

5. a) False; the r tells the clustering around the SD line, not percentages.

f) False; the association is not causation.

g) True; the correlation tells on average or in general what happens.

h) True; the r for x and y = r for y and x.

i) False; r doesn’t give percentages.

6. Dotted = SD, dash predicts y so it is the regression line for y on x, solid = regression line for x on y.

7. Sounds like the regression affect—both are wrong.

8. Regression doesn’t explain a change in the AVERAGE—it looks like people are less nervous on the 2nd reading.

9. a) and b) are scanned separately as Unit 3 (or III) Scan.

j) If the midterm is 50%, then you would expect the final to be 50%.

k) Unknown midterm percentile; expect the average = 50%.

10. False; the student will regress toward the average. So the 2nd year GPA’s will be between 40 and 50%.

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