The mathematical question is answered if a classical hit function could be approximated 1st by others with variable hit number and a given target and 2nd-ly by others with variable target and a given hit number. Under certain restricting presumptions there exist both possibilities even for the one hit function. In the 2nd case a general expression is deduced which describes the distribution of targets in object mixtures. It is discussed in detail for exponential mixtures where a strong asymmetry of distribution can result. Simple hit formulas, also the one hit formula, should only be used if there could be excluded an eventual hidden misleading variability of biological objects.