18. The following data lists eight different investment amounts (X) and the amount of interest they earned (Y): X $1000 $2000 $3000 $ 10000 $500 $5000 Y $50 $100 $150 $500 $25 $250 What is the best estimate for the regression coefficient r between X and Y? a) r will be positive and close to zero b) r will be positive and close to one c) r will be exactly one d) r will be larger than one e) r will be negative 19. In a study of possible correlation between the height in cm (X) and weight in kg (Y) of chimpanzees, a sample of 40 animals produces a correlation coefficient of r=+0.813 and a regression line with equation Y = 034X + 19 5. What is the expected weight of an 80 cm tall chimpanzee? a) 46.7 kg b) 177.9 kg c) 24.0 kg d) 34.8 kg e) 57.1 kg 20. The following table lists the number of days that five houses had been up for sale, as well as their selling price. X (days) 45 12 3 17 32 Y (1000$) 275 401 420 212 365 Calculate the correlation coefficient r between the number of days (X) and the selling price (Y) for this sample. a) - 0.465 b) - 0.219 c) + 0.219 d) + 0.512 e) + 0.897 21. The Vitamin C content of a particular brand of vitamin supplement pills is normally distributed with mean 490 mg and standard deviation 12 mg. What is the probability that a randomly selected pill contains at least 500 mg of Vitamin C? a) 0.7967 b) 0.8333 c.) 0.0525 d) 0.1123 e) 0.2033