Five years ago XYZ International issued some 25-year zero-coupon bonds that were priced with a market's required yield to maturity of 8 percent and a par value of $1,000. What did these bonds sell for when they were issued? Now that 5 years have passed and the market's required yield to maturity on these bonds has climbed to 10 percent, what are they selling for? If the market's required yield to maturity had fallen to 6percent, what would they have been selling for?