A group of health researchers followed a group of nurses in Chicago, and found that those who regularly got 7 or more hours of sleep had lower incidence of several types of cancer. Answer the following questions: Is this a study or an experiment? How do you know? Does this mean that a lack of sleep causes cancer? If yes, how do you know? If no, what is a possible lurking or confounding variable?

Let us imagine that the number of automobile accidents in a certain region are related to the regional number of registered automobiles in tens of thousands (b1), alcoholic beverage sales in $10,000 (b2), and decrease in the price of gasoline in cents (b3). furthermore, imagine that the regression formula has been calculated as: y = a + b1x1 + b2x2 + b3x3 where y = the number of automobile accidents, a = 7.5, b1 = 3.5, b2 = 4.5, and b3 = 2.5 calculate the expected number of automobile accidents for a football weekend if the region has 25,000 registered vehicles, $75,000 worth of beer is sold, and a gas war causes a 10 cent drop in a gallon of gas.