Should we always assume that it’s equal to 75% of time to maturity when the question does not say anything about the percentage.
That’s apparently the position of CFA Institute.
However, I believe that it’s far more likely that they’ll tell you the duration. There’s no point in having you guess at it.
Yes, unless otherwise noted or given in the question prompt, “the duration of [a one-year] fixed-rate bond is approximated as 75% of its maturity”, or 0.75. (Reading 29 Risk Management Applications of Swap Strategies, page 360).
If we’re talking about a 2-year fixed-rate bond, we would use a duration of 2 * 0.75 = 1.50.
If we’re talking about a 3-year fixed-rate bond, we would use a duration of 3 * 0.75 = 2.25.
And so on…
Hope this helps!
OMGMileyCyrus
Thank you