[clevermartin]

I have done an experiment in school to determine:
the partition coefficient of ethanoic acid between water and 2-methylpropan-1-ol

In the experiment, I used pipette to measure 25cm³ of ethanoic acid and 25cm³ of 2-methylpropan-1-ol, to put into the separating funnel.
However, my teacher mentioned that the amounts of aqueous ethanoic acid and 2-methylpropan-1-ol placed in the funnel need not to be measured out accurately, while the volumes of the aqueous and alcohol solution used in the titration must be known accurately...

What is the point for not necessary to measure the the amounts of aqueous ethanoic acid and 2-methylpropan-1-ol placed in the funnel accurately?