3: A parent group examines 25 randomly selected PG-13 movies and 25 randomly selected PG movies, records the number of sexual innuendos and curse words that occur in each, and then compares the number of sexual innuendos and curse words between the two movie ratings. Is this an observational study or an experiment? If it is an observational study, what type of study is it? Q4: The Cancer Prevention Study II (CPS-II) examines the relationship among environmental and lifestyle factors of cancer cases by tracking approximately 1.2 million men and women. Study participants completed an initial study questionnaire in 1982 providing information on a range of lifestyle factors, such as diet, alcohol and tobacco use, occupation, medical history, and family cancer history. These data have been examined extensively in relation to cancer mortality. The vital status of study participants is updated biennially. Is this an observational study or an experiment? If it is an observational study, what type of study is it? 7: The Empirical Rule Suppose that a certain brand of light bulb has a mean life of 600 hours and a standard deviation of 53 hours. (a) A histogram of the data indicates the sample data follow a bell-shaped distribution. According to the Empirical Rule, 99.7% of light bulbs have lifetimes between ______ and ______ hours. (b) Assuming the data are bell shaped, determine the percentage of light bulbs that will have a life between 494 and 706 hours. (c) Assuming the data are bell shaped, what percentage of light bulbs will last between 547 and 706 hours. (d) If the company that manufactures the light bulb guarantees to replace any bulb that does not last at least 441 hours, what percentage of light bulbs can the firm expect to have to replace, according to the Empirical Rule? (e) Would it be unusual for a light bulb to last 750hours? How about 450hours?

Basketball Spreads: In sports betting, Las Vegas sports books establish winning margins for a team that is favored to win a game. An individual can place a wager on the game and will win if the team bet upon wins after accounting for the spread. For example, if Team A is favored by 5 points and wins the game by 7 points, then a bet on Team A is a winning bet. However, if Team A wins the game by only 3 points, then a bet on Team A is a losing bet. For NCAA Division I basketball games, a least-squares regression with explanatory variable home team Las Vegas spread, x, and response variable home team winning margin, y, is =1.0070.012 Source: Justin Wolfers. "Point Shaving: Corruption in NCAA Basketball" (a) Predict the winning margin if the home team is favored by 3 points. (b) Predict the winning margin (of the visiting team) if the visiting team is favored by 7 points (this is equivalent to the home team being favored by 7 points). (c) Interpret the slope. (d) Interpret the y-intercept. (e) What key pieces of information are missing from this question? Q9: A researcher collects data regarding the percent of all births to unmarried women and the number of violent crimes for the 50 states and Washington, DC. The scatter diagram along with the least-squares regression line obtained from Minitab is shown. The correlation between percent of births to unmarried women and the number of violent crimes is 0.667. For 99% confidence with a sample size of 50, the critical value for the correlation coefficient is 0.361. (a) Is the correlation significant? A politician looks over the data and claims that, for each 1% decrease in births to single mothers, violent crimes will decrease by 23. Therefore, percent of births to single mothers needs to be reduced in an effort to decrease violent crimes. (b) Is there anything wrong with the reasoning of the politician? Explain.