Population Genetics Question
Question is: If an Ashkenazi(1/30) and(multiply) French-Canadian(1/30) ....
Where 1/300 came from ?

I duno, I may missing something - but may it be like  that

Parrent1(=1/30 * 1/2)*Parrent2(=1/30 * 1/2) = P(child with both mutations)