There are 40 total alleles of the 20 people of which 2 alleles are cystic fibrous causing.
2/40 = .05 the ¦ of the cystic fibrous allele thus cc or q2 = (.05)2 =.0025 or .25% of the population will be born with cystic fibrous.
thus cc or q2 = (.05)2 =.0025 or .25% of the population will be born with cystic fibrous.