You compare two strands of mtDNA and discover that there are 3 differences in base pairs between them. Assuming that the mutation rate for the species that you are examining is 1 mutation every 20,000...

Extracted text: You compare two strands of mtDNA and discover that there are 3 differences in base pairs between them. Assuming that the mutation rate for the species that you are examining is 1 mutation every 20,000 years, how long ago did the two strands share a common ancestor? Write your answer in xx,Xxx format. These two strands shared a common ancestor years ago.