Solution :
The population of the interest is : All smokers
The parameters of the interest is : population mean number of the cigarettes per day.
Population of interest :
The population interest is defined as the group or the population form the sample from which the experimenter or the researcher draws results or the conclusion of the experiment.
In the context, the researcher wants to draw the results from all the smokers in the study, so the population of interest is the smokers.
Parameter of interest :
The parameters of interest is the set of all unknown numbers which describes the population from which the researcher wishes to test with the estimator.
In the context, the interest parameter is the mean or the average population number of the cigarettes per day.