# Answers_to_Exercises_on_Correlation - who have high...

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Answers Multiple -Choice Questions 1. c 2. b Fill -In Questions 1. tiredness 2. a negative correlation Problems 1. a. scatterplot b. positive linear correlation c. X (Eggs) Y X- Xm Y – Ym (X – Xm)(Y – Ym) 2 210 0 20 0 0 100 -2 -90 180 1 180 -1 -10 10 5 270 3 80 240 x = 8 y = 760 = 430 mean = 2 mean = 190 Sx = 1.87 Sy = 61.24 COV = (X – Xm)(Y – Ym) / n COV = 430 / 4 = 107.5 r = COV / SxSy r = 107.5 / (1.87)(61.24) r = 107.5 / 114.52 r = 0.94 d. Example answer : Eating eggs could cause higher cholesterol ; people

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Unformatted text preview: who have high cholesterol may choose to eat more eggs ; some third variable, such as upbringing or genetic influences may have the effects of making people have high cholesterol and also a liking for eggs. 2. a. Scatterplot b. X Y X- Xm Y – Ym (X – Xm)(Y – Ym) 6 7 -1 1 -1 8 8 1 2 2 3 1 -4 -5 20 10 8 3 2 6 8 6 1 0 0 x = 35 y = 30 = 27 mean = 7 mean = 6 Sx = 2.36 Sy = 2.61 COV = 27 / 5 = 5.4 r = 5.4 / (2.37)(2.61) r = 5.4 / 6.19 r = 0.87...
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• Winter '10
• AfroditiPanagopoulos
• Harshad number, high cholesterol, positive linear correlation, a. scatterplot b., negative correlation Problems

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