Arrivals Will your flight get you to your destination on time? The U.S. Bureau of Transportation Statistics reported the percentage of flights that were late each month from 1995 through September of 2011. Heres a histogram, along with some summary statistics: We can consider these data to be a representative sample of all months. There is no evidence of a time trend 1r = 0.072. a) Check the assumptions and conditions for inference about the mean. b) Find a 99% confidence interval for the true percentage of flights that arrive late. c) Interpret this interval for a traveler planning to fly.

Important Terms Observational Study Data gathered by only witnessing individuals without guiding or stating an input on them. Designed Experiment Data gathered by an examiner on individuals then runs trials each to test one or more variables. Cofounding Variables existing variables within the student that affect the response Randomization randomly assigned themes to experiments Theoretical Method Divide the number of results in the experiment taken by total number results Empirical Method Calculating the relative frequency Relative Frequency X/n X number of successes n number of results Response and Explanatory Variables X= Response Variable = dependent Y= Explanatory Variable Independent Goal X is what causes the change in Y Probability