How do you do probabilities with punnett squares?
The number of squares with the outcome divided by the total number of squares. This can be expressed as a fraction or percentage.
A Classic example is the bi hybrid cross of both parents being brown /blonde
Mother B b Father
B | B B | B b |
b | b B | b b |
There is one off spring square bb that will give rise to a blonde
off spring There are four total squares.
So the probability is 1/4 of having a blonde child This translates to a 25% probability of having a blonde.
There are three square that will result in a brown haired offspring.
so the probability of a a brown haired off spring is 3 out of 4 or
3/4 or 75 %