21 Suppose a professor records the number of days absent and

21) Suppose a professor records the number of days absent and the final exam score for the students in his class. Use this data in the table below to answer the following questions.

No. of Absences, X 0 1 2 3 4

Final Exam Scores, Y 84.1 84.6 75.2 75.7 66.3

(a) Find the least-squares regression line, treating number of absences as the explanatory variable and final exam score as the response variable.

y = _X + _

(b) Interpret the slope and intercept, if appropriate

A) The slope indicates the average change in final exam score for an additional absence.

B) The slope indicates the average number of absences

C) The slope indicates the average final exam score

D) The slope indicates the ratio between the average final exam score and the average number of absences

E) It is not appropriate to interpret the slope because it is not equal to zero

(c) Choose the best interpretation for the y-intercept

A) The y-intercept indicates the average final exam score for a student with no absences.

B) The y-intercept indicates the final exam score of the student with the most absences.

C) The y-intercept indicates the average final exam score for the population.

D) The y-intercept indicates the average number of absences for the population.

E) It is not appropriate to intercept the y-intercept because it is outside the scope of the model.

(d) Predict the final exam score for a student who misses one class period and compute the residual. Is the final exam score above or below average for this number of absences?

The predicted final exam score is _. (Round to two deciaml places as needed)

The residual is _

(e) What is the best desciption for the final exam score for this number of absences.

A) The final exam score is below average because it is below the regression line.

B) The final exam score is above average because it is below the regression line.

C) The final exam score is above average because it is above the regression line.

D) The final exam score is below average because it is above the regression line.

(f) Draw the least-squares regression line on the scatter diagram of the data and label the residual.

Solution

21) Suppose a professor records the number of days absent and the final exam score for the students in his class. Use this data in the table below to answer the following questions.

No. of Absences, X 0 1 2 3 4

Final Exam Scores, Y 84.1 84.6 75.2 75.7 66.3

Regression Analysis

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