What is the relationship between the amount of time statistics students study per week and their final exam scores? The results of the survey are shown below. Time8 7 16 7 15 4 7 3 5 Score 83 86 100 79 100 63 84 78 66 Find the correlation coefficient:  r=r=    Round to 2 decimal places. The null and alternative hypotheses for correlation are: H0:H0:      == 0 H1:H1:       ≠≠ 0     The p-value is:    (Round to four decimal places)

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What is the relationship between the amount of time statistics students study per week and their final exam scores? The results of the survey are shown below.

Time8 7 16 7 15 4 7 3 5

Score 83 86 100 79 100 63 84 78 66
  1. Find the correlation coefficient:  r=r=    Round to 2 decimal places.
  2. The null and alternative hypotheses for correlation are:
    H0:H0:      == 0
    H1:H1:       ≠≠ 0    
    The p-value is:    (Round to four decimal places)
  3. Use a level of significance of α=0.05α=0.05 to state the conclusion of the hypothesis test in the context of the study.
    • There is statistically insignificant evidence to conclude that there is a correlation between the time spent studying and the score on the final exam. Thus, the use of the regression line is not appropriate.
    • There is statistically significant evidence to conclude that there is a correlation between the time spent studying and the score on the final exam. Thus, the regression line is useful.
    • There is statistically significant evidence to conclude that a student who spends more time studying will score higher on the final exam than a student who spends less time studying.
    • There is statistically insignificant evidence to conclude that a student who spends more time studying will score higher on the final exam than a student who spends less time studying.
  4.  r2r2 =  (Round to two decimal places)  
  5.  Interpret r2r2 :  
    • There is a 78% chance that the regression line will be a good predictor for the final exam score based on the time spent studying.
    • 78% of all students will receive the average score on the final exam.
    • There is a large variation in the final exam scores that students receive, but if you only look at students who spend a fixed amount of time studying per week, this variation on average is reduced by 78%.
    • Given any group that spends a fixed amount of time studying per week, 78% of all of those students will receive the predicted score on the final exam.
  6. The equation of the linear regression line is:   
    ˆyy^ =  + xx   (Please show your answers to two decimal places)  
  7. Use the model to predict the final exam score for a student who spends 9 hours per week studying.
    Final exam score =  (Please round your answer to the nearest whole number.)  
  8. Interpret the slope of the regression line in the context of the question:  
    • As x goes up, y goes up.
    • The slope has no practical meaning since you cannot predict what any individual student will score on the final.
    • For every additional hour per week students spend studying, they tend to score on averge 2.48 higher on the final exam.
  9. Interpret the y-intercept in the context of the question:
    • The average final exam score is predicted to be 62.
    • If a student does not study at all, then that student will score 62 on the final exam.
    • The y-intercept has no practical meaning for this study.
    • The best prediction for a student who doesn't study at all is that the student will score 62 on the final exam.
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