What is the relationship between the number of minutes per day a woman spends talking on the phone and the woman's weight? The time on the phone and weight for 8 women are shown in the table below.   Time 82 24 64 52 82 12 77 89 Pounds 181 125 156 142 158 103 148 161   Find the correlation coefficient:  r=r=    Round to 2 decimal places. The null and alternative hypotheses for correlation are: H0:H0: ? μ ρ r  == 0 H1:H1: ? r ρ μ   ≠≠ 0     The p-value is:    (Round to four decimal places) 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 women spend on the phone and their weight. Thus, the use of the regression line is not appropriate. There is statistically insignificant evidence to conclude that a woman who spends more time on the phone will weigh more than a woman who spends less time on the phone. There is statistically significant evidence to conclude that there is a correlation between the time women spend on the phone and their weight. Thus, the regression line is useful. There is statistically significant evidence to conclude that a woman who spends more time on the phone will weigh more than a woman who spends less time on the phone.

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What is the relationship between the number of minutes per day a woman spends talking on the phone and the woman's weight? The time on the phone and weight for 8 women are shown in the table below.

 

Time 82 24 64 52 82 12 77 89
Pounds 181 125 156 142 158 103 148 161

 

  1. Find the correlation coefficient:  r=r=    Round to 2 decimal places.
  2. The null and alternative hypotheses for correlation are:
    H0:H0: ? μ ρ r  == 0
    H1:H1: ? r ρ μ   ≠≠ 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 women spend on the phone and their weight. Thus, the use of the regression line is not appropriate.
    • There is statistically insignificant evidence to conclude that a woman who spends more time on the phone will weigh more than a woman who spends less time on the phone.
    • There is statistically significant evidence to conclude that there is a correlation between the time women spend on the phone and their weight. Thus, the regression line is useful.
    • There is statistically significant evidence to conclude that a woman who spends more time on the phone will weigh more than a woman who spends less time on the phone.
  4.  r2r2 =  (Round to two decimal places)  
  5.  Interpret r2r2 :  
    • Given any group of women who all weight the same amount, 84% of all of these women will weigh the predicted amount.
    • 84% of all women will have the average weight.
    • There is a large variation in women's weight, but if you only look at women with a fixed weight, this variation on average is reduced by 84%.
    • There is a 84% chance that the regression line will be a good predictor for women's weight based on their time spent on the phone.
  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 weight of a woman who spends 59 minutes on the phone.
    Weight =  (Please round your answer to the nearest whole number.)  

  8. Interpret the slope of the regression line in the context of the question:  
    • For every additional minute women spend on the phone, they tend to weigh on averge 0.76 additional pounds.
    • The slope has no practical meaning since you cannot predict a women's weight.
    • As x goes up, y goes up.


  9. Interpret the y-intercept in the context of the question:
    • The average woman's weight is predicted to be 101.
    • The y-intercept has no practical meaning for this study.
    • If a woman does not spend any time talking on the phone, then that woman will weigh 101 pounds.
    • The best prediction for the weight of a woman who does not spend any time talking on the phone is 101 pounds.
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