So this is is not really a good question from the start then.
In a way. First of all such titration makes no sense. If the question was "check if it makes sense" it will make sense.
I hope you will find sense in the above
If you don't know the Ka and you are only assuming the final volume of the solution (what if you had added water during the titration, for example to wash the sides of the flask etc?)
Lack of Ka is less problematic. I am against giving all Ka values every time they are needed, as in real life you have to judge for yourself what data you need to find answer. The easiest way to paralyze students that are always given necessary constants is to not give the data or to give some excess information. They will spend hours trying to use that excess data.
IMHO instead of listing Ka in the text of the question it should be given in some external data sheet for use throughout the chemistry course. Look for example for chemistry data sheet at Roy Jensen's page
As for volume - on the general level you are right. But then all titration questions are simplified when compared to the real world so I will not bother myself with such details and I will treat assumption on the volume (sum of sample and titrant) as valid.
On the sidenote, one may prepare some interesting questions on the usability of indicators, depending on the dilution of the sample, and the concentration of titrant used.