Question: The airline industry is interested in estimating the average weight of luggage [both checked & carry on] brought by an individual passenger for a cross-country flight. Experience has shown that the length of time a passenger will be away from home affects how much luggage she will carry on a flight. A random sample of 500 passengers who were traveling from their home airport on a cross-country, round-trip ticket was selected. Each passenger’s checked & carry-on luggage was weighted. Here are some summary statistics for this sample:
Note: A scatter plot of data reveals a correlation of 0.63 between trip duration & weight of luggage.
[A] Could the distribution of trip duration be approximately normally distributed? Justify your answer.
[B] What assumption/conditions must be met in order to compute a 99% confidence interval for the mean trip duration of passengers leaving their home airports on round-trip, cross-country flights? Discuss whether each of these assumptions/conditions is satisfied in this case.
[C] Suppose each passenger is given a two-pound deli snack to carry onto the plane. Now each passenger’s total luggage weight has increased by 2 pounds. What effect will this have on the correlation coefficient? Justify your answer.
[D] Find the equation of the least-squares regression line for predicting luggage weight from trip duration. Show your method.
[E] Intercept the slope and y-intercept of your least-squares regression line from part (d) in the context of this problem.