Question

Consider the estimated equation from your textbook. Answer Questions 18 & 19. Test Score = 698.9 -2.28 STR (10.4) (0.52) RP = 0.051 SER = 18.6 18. What is prediction of test score for STR=4? (a) 689.78. (b) 456.87. (c) 298.25. (d) 265.20. 19. How would the estimated test score would change is STR increased from 4 to 6? (a) would decrease by 4.56 points. (b) would increase by 4.56 points. (c) would decrease by 2.56 points. (d) would increase by 2.56 points.

Trying to find out how to come about the answers showing the work, formulas, step-by-step process.

Answer 1

18) from given equation :testScore =698.9-2.28*STR

at STR =4 , predicted value of TestScores=698.9-2.28*4 =689.78

option A is correct

19) as change in test scores for a unit change in STR =slope of the regression line = -2.28

therefore change in test scores for 2 unit change in STR (from 4 to 6)=2*(-2.28)= -4.58

hence option A is correct (as negative sign indicate decrease in test scores)