by means of fractional life periord i understand you mean half life periord.
Half Life Period is defined as the time taken for half of the reaction to be completed i.e. the time in which the concentration of a reactant is reduced to half of its original value is called Half Life Period of the reaction.
General expression for half life period of a reaction of nth order will be as follows:
For zero order, t1/2 α [A0]
For 1st order, t1/2 α [A0] 0
Similarly for 2nd order, t1/2 α [A0] -1 and so on
In general, for a reaction of nth order:
t1/2 α [A0] 1-n
t1/2 α 1/ [A0] n- 1
and as far as i understand the word fractional its just used for prediction as in world of chemical some of plus or minus time will take a part due to temprature or pressure is not constant. so with 100% accuracy will not able to predict in time periord I am not 100 % sure you may ask to your Teacher or sir but by word fraction is mostly used for genralization.