Answer:
If one is analyzing a solution, for the best accuracy, the volume of titrant used should fall in the upper range of the burette that delivers the titrant. If one is using a 50 ml burette, one would like the volume to fall in maybe the 30 to 45 ml range. If on the first trial, the volume of titrant used is only a few ml, then a larger volume of solution being analyzed should be taken. If the volume of titrant exceeds 50 ml, then a smaller volume of solution should be taken. One should not need three trials. Based on the first trial, one should be able to determine the optimum volume of solution to be analyzed. If one is lucky, the optimum amount may occur on the first trial.