Yes I can only try, that’s the correct answer.
He assumed it was 8% (4% chance that he was not a carrier + 4% that she is not a carrier = 8%), he happened to be close though.
The method I used was 1 – .96 * .96 = .0784 or 7.84%.
He did not feel it was worth it for such a small chance. I felt that I didn’t have the qualifications to convince him otherwise but I strongly convinced him to speak to a rov (which at first he refused to).
The rov from Dor Yeshorim who told them the news advised them to not speak with each other anymore and any communication between the two of them should go through him, the shadchan or another competent person. For obvious reasons he did not tell the shadchan what happened (he didn’t feel it was right to have the shadchan know that she was a carrier) he just said “thank you” and that he would highly recommend the girl to anyone else but they are not meant for each other.
He found out through the rov that she went for additional testing and he felt he owed it to her to go for the additional testing also.
The results were that they are not compatible.
I don’t know who she is but I heard that she got married.
He is married with some kids.