Profits from recycling paper, cardboard, aluminum, and glass at a liberal arts college have increased at a constant rate of $1,200 in each of the last three years. If this year's profit (end of year 1) is expected to be $6,000 and the profit trend continues (i.e. the profit at the end of year 2 is $7,200 and so on) for four years, find the present worth of the profit at an interest rate of 9% per year.