The answer is A. 72.25 percent.
The Hardy-Weinberg principle can be used:
p² + 2pq + q² = 1 and p + q = 1
where p and q are the frequencies of
the alleles, and p², q² and 2pq are the
frequencies of the genotypes.
The r allele (q) is found in 15% of the population:
q = 15% = 15/100
Thus, q = 0.15
To calculate the R allele frequency (p), the formula p + q = 1 is
used:
If p + q = 1, then p = 1 - q
p = 1 - 0.15
Thus, p = 0.85
Knowing the frequency of the R allele (p), it is easy to determine the
frequency of the RR genotype (p²):
p² = 0.85² = 0.7225
Expressed in percentage, p² = 72.25%.
