Derivatives Sample #2

I refer to the question that deals with increasing bond allocation and decreasing stock… I don’t remember except that when I see the solution, they have used cash duration as 0.25. But on page 113 of the text book, similar problem has used cash duration of 0 when increasing the bond allocation. What am I missing ? When should I use 0.25 and when 0 ? I did a search on cash duration… but didnt find anything that answers my question… Thanks!

^^^ The cash duration was specified as 0.25 in the table.

I don’t have the book in front right now, but the example problem states something like because we don’t use real cash transactions the duration is zero… I might even be hallucinating…given all the craziness at work… but I vaguely recall reading that. I will get back home, read the pages again and post here. Meanwhile anyone has more conceptual knowledge of this cash duration thing ? Thanks!