The determination of a test for the equality of Means for two Normal Distributions with different Variances given samples from each. There exists an exact test which, however, does not give a unique answer because it does not use all the data. There also exist approximate tests which do not use all the data.
See also Normal Distribution
References
Fisher, R. A. ``The Fiducial Argument in Statistical Inference.'' Ann. Eugenics 6, 391-398, 1935.
Kenney, J. F. and Keeping, E. S. ``The Behrens-Fisher Test.'' §9.8 in Mathematics of Statistics, Pt. 2, 2nd ed.
Princeton, NJ: Van Nostrand, pp. 257-260 and 261-264, 1951.
Sukhatme, P. V. ``On Fisher and Behrens' Test of Significance of the Difference in Means of Two Normal Samples.'' Sankhya 4,
39, 1938.