9. Walking in the Airport, Part I Do people walk faster in the airport when they are departing (getting on a plane) or when they are arriving (getting off a plane)? Researcher Seth B. Young measured the walking speed of travelers in San Francisco International Airport and Cleveland Hopkins International Airport. His findings are summarized in the table. Direction of Travel Departure Arrival Mean speed (feet per minute) 260 269 Standard deviation (feet per minute) 53 34 Sample size 35 35 Source: Seth B. Young. "Evaluation of Pedestrian Walking Speeds in Airport Terminals." Transportation Research Record. Paper 99-0824. a. Is this an observational study or a designed experiment? Why? b. Explain why it is reasonable to use Welch's t-test. c. Do individuals walk at different speeds depending on whether they are departing or arriving at the a = 0.05 level of significance