Use the following information to answer questions 4-8. A study wants to look at

Question

Use the following information to answer questions 4-8. A study wants to look at the correlation between sugar consumption and the development of cavities. The table below shows the average daily intake of sugar (g) and the total number of cavities per patient over the one-year study period. Daily Sugar Intake Number of Cavities m 25 80 3 120 10 110 4. What is the sample correlation coefficient given y2.1(x-x9 11221.43, E2.10 -y a, 0.35 b, 0.70 c. 0.87 d. -0.45 5. What type of correlation does this represent? a Strong positive b, Strong inverse c. Weak inverse d. No correlation The investigator wants to construct a regression equation based on his current sample to be able to predict the number of cavities that a patient develops based only on their sugar intake given the standard deviation for the daily sugar intake is 43.25 and the standard deviation for the number of cavities is 1.41.

Explanation / Answer

4) correation coefficient =Sxy/(SSx*SSy)1/2 =320/(11221.43*12)1/2 =0.872

5) strong positive

6)slope =Sxy/SSx =320/11221.43 =0.0285 option D

7)Y intercept =Ybar-Xbar*b1 =2-60.7*0.03=0.2686 option A

8)predicted value =0.2686+0.0285*45=1.55 option B

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