How to estimate Duration? 2010, following, contract, example

NakedPuts

Ok, I've been having trouble with estimating duration.

I know that for Swaps, you do 3/4 the maturity for the Fixed Rate and 1/2 the reset date on the variable.

What about for other types of instruments? Take Question 6 2010 Level 3 Exam for example:

The duration of the GIC contract is 4 which is equal to it's maturity.

I'm guessing I'm supposed to use the following tree to decide which duration method to use:

1. If it's given, use the given
2. If it's a swap, use the 3/4 fixed maturity and 1/2 variable reset method
3. If it's neither, just use the maturity

Is this correct?