A UK lottery prize pays £2000 at the end of the first year, £3000 at the end of the second year, £4000  at the end of the third year, and so on for 25 years.   If this is the only prize in a lottery, 20,000 tickets  are sold, and you could invest your money elsewhere at 10% interest rate (compounded annually),  how much is each ticket worth, on average?