1. The duration model has some problems. Which of the following is NOT one of them
   1. It creates a problem when actual and anticipated cash flows arrive at different times.
   2. Continuous buying and selling of securities makes it cumbersome and costly to update duration all the time.
   3. Duration changes as the time to maturity changes, making it difficult to maintain a continuous hedge.
   4. It distorts the prices for large changes in interest rates.
   5. It assumes an upward-sloping term structure, but the term structure can also be flat or downward-sloping.