I need to convert 150 Frequency domain samples to the time domain. The problem is, I have been provided with 250 time domain samples for comparing my results.  How am I supposed to relate the 150 samples to 250 samples? I can't find any relationship like interpolation/decimation between the two.

Does this have anything to do with windowing (hamming,hanning,etc), sampling frequency, min and max frequency in the original signal?