A group of scientists determines that a mitochondrial DNA sequence shared by two species has a constant mutation rate. The sequences of mitochondrial DNA for the two species are shown below.

Species A: GACTGGGCATTA
Species B: GACCGGACATGA

Using the principles of molecular clocks and a known mutation rate for this sequence, the scientists determine that these species diverged from a common ancestor 30 million years ago. Based on this information, how much longer do you predict it would take these species to differ by a total of seven base pairs?

Question

A group of scientists determines that a mitochondrial DNA sequence shared by two species has a constant mutation rate. The sequences of mitochondrial DNA for the two species are shown below.
 
Species A: GACTGGGCATTA
Species B: GACCGGACATGA
 
Using the principles of molecular clocks and a known mutation rate for this sequence, the scientists determine that these species diverged from a common ancestor 30 million years ago. Based on this information, how much longer do you predict it would take these species to differ by a total of seven base pairs?

anonymous · Answer

A. 60 million years
B. 20 million years
C. 140 million years
D. 80 million years

I know it's not 140 million, and I don't think it's 20 or 60, so I think it's 80 but I'm not sure.