27. The prices of the snackfood items sold by a large supermarket chain have mean ,u = $3.34 and standard deviation 0 = $0.12. We want to take an SRS such that the sample mean has a standard deviation of 0.03. How many samples do we need? 15. For the same data in the previous question, suppose m is measured in US dollars. If the unit of m is changed from US dollars to euros (1 euro = 1.3 US dollars), the slope of the new regression line is? 16. A study shows that the quality of hospitals (better equipment, better doctors) is positively correlated with the number of patients who died in them. Why is this happening? 0 What could be a lurking variable? 12. Parents recorded children's height at various ages between 36 and 66 months, Below is a record of the results: Age (months) 36 48 54 60 66 Height (inches) 34 38 41 43 45 A Find the least squares regression line explaining how height depend on age. (in, 37, 3m, 3y, 7', intercept and slope) B John's parents decide to use the leastsquares regression line based on the data in the previous problem to predict his height at the age of 1 year old. What can be said? 13. The correlation between cc and y is found to be 0.7. Which of the following is right? A The regression line of 3; on :1: explains more than 50% of the variation in y. B The correlation between a: + 10 and y is 0.7. C Any outlier in as will always make the correlation higher. D The correlation between 0.533 and y is 0.35