Final answer:
The promised yield to maturity for the 15%, 20-year bond is d. 17.77%.
Step-by-step explanation:
Yield to maturity (YTM) is the total return anticipated on a bond if it is held until it matures. To calculate the YTM, we can use the formula:
YTM = (Annual Interest Payment + (Face Value - Current Price) / Number of Years) / ((Face Value + Current Price) / 2)
For this 15%, 20-year bond with a current price of $850, the YTM can be calculated as follows:
YTM = (15% + ($1,000 - $850) / 20) / (($1,000 + $850) / 2) = 17.77%
Therefore, the promised yield to maturity for this bond is 17.77%, which corresponds to option d.