Final answer:
The mean fitness at this locus within this population is 0.95.
Step-by-step explanation:
The mean fitness at this locus within this population can be calculated by multiplying the frequency of each genotype by their respective fitness and then summing the products.
Genotype frequency 1: 0.75 x 1.0 = 0.75
Genotype frequency 2: 0.25 x 0.8 = 0.2
Total fitness: 0.75 + 0.2 = 0.95
Therefore, the mean fitness at this locus within this population is 0.95.