Product law- the provavility of 2, or more, independant events occurring together, is the product of each of those events occurring alon.

Sum law- When there is more than 1 combination of ways for an event to occur, the probability is the sum of those ways.

Is there only 1 way for this to happen?
Yes-Multiply
No- I.O. of all the combos- multiply each one-Add the combos together

I. The Monohybrid Cross
Parental (P)               true-breeding tall blant  x   true-breeding dwarf


1st Filial(F1)   All Tall       Tall  x  Tall


2nd Filial(F2)                        Tall: Dwarf   3:1 (75%) (25%)
( Interbreeding of f1's)


Key
A=Tall
a= Dwarf

A+a
Aa* Aa