What is the value in dollars of a derivative that pays off $£ 10,000$ in 1 year provided that the dollar/sterling exchange rate is greater than 1.5000 at that time? The current exchange rate is 1.4800 . The dollar and sterling interest rates are $4 \%$ and $8 \%$ per annum, respectively. The volatility of the exchange rate is $12 \%$ per annum.