What determines if a mutation is passed on within a population

Reproduction rate and population size helps determine how fast the mutation is passed within a population. Also if it is favorable to species it helps determine if it is passed and unfavorable mutations tend to die off. Think about for example if one species has a favorable environment gene then it's going to have a higher chance or survival and reproduction than the other species. Also genes help determine if mutation is passed on. 

Ithink that its like 15 mph.