Question

114 Escherichia coli are on my right index finger. I lisck my finger and accidently eat 13 of them.  

12 Escherichia coli are on my left thumb, what is the probability that I will eat some when I lick my thumb?

Answer 1

here the question is related to the genetic drift. genetic drift applies to only small populations.

when 114 E.coli were there on the index finger, 13 were eaten by the person in a accidental way when that finger was licked. index finger is comparatively smaller than the thumb in the size. here the population of the E.coli on the index finger is larger than the population of E.coli on the left thumb.

As small population of E.coli are present on large area there is very less probability that they get eaten if the thumb is licked. if all of them are present at one place then there is more probability that they can get eaten or they will not get eaten if that area is not licked at all.

Thus the small population either easily get affected/not affected by an environmental effect if the population is located at a confined small place. if the population is scattered then very less chances are there that they will get affected by the environmental impact.