Biology — Genetic Probability

P(\text{A and B}) = P(\text{A})\times P(\text{B})

P(\text{A or B}) = P(\text{A}) + P(\text{B})

\text{dihybrid: } (3{:}1)^2 = 9{:}3{:}3{:}1

\text{use a Punnett square}