At the beginning of 1998, the population of the United States was 268, 924, 000 and growing at the rate of 1, 856, 000 per year. The annual per capita consumption of gasoline in the United States was 52.3 gallons and growing at the rate of 0.2 gallons per year. At what rate was the total annual consumption of gasoline increasing at that time? [Hint: total annual consumption = population annual per capita consumption.]

Postal regulations state that the length plus girth of a mailable package can be no more than 84 inches. Determine the dimensions of the square-ended rectangular package of greatest volume that is mailable.