(a) The variation of the size of a commercial jet is 200 seats plus-minus . The variation of the fuel consumption is 60 passenger miles per gallon plus-minus. The correlation is -0.48. Find the covariance, show work, and report its units.

(b) You don't know the distribution of the plane sizes from (a) but suspect that it does not follow the bell curve. If you want to capture 75% of all the planes in the population, how many standard deviations around the mean should you allow? Show the formula and the solution.

(c) Discuss briefly but substantively what would change if the plane sizes followed a bell curve: most planes had around 200 seats, and fewer planes had 150 or 250, and even fewer 100 or 300. How would that change the number of standard deviations needed to encompass 75% of observations? (no numbers necessary)