If a man w. blood type B, whose parents are O, marries a woman w. AB,what will be the % of their kids w. B?

Answer 1

Each conception has a 50% chance of being either B or AB.

BTW, 2 O people can't have a B child. O is recessive to B. 2 O people will only have O children.

Answer 2

If Both of his parent's are O, he can't be B. However, if one parent is O, then he can be blood type B (genetically he would be BO and B is dominant to O)

Which means his children would be genetically 50% AB, 25% BB and 25% BO. So 50% of the kids would be blood type B (BB and BO).

If he is BB (which he can't be unless he's adopted), his kids would be 50% AB and 50% BB. Blood types AB and B.

Answer 3

I'm confused. If both of the man's parents have a phenotype of O blood then their genotype is OO. The man should also have O phenotype, not B. This is the punnett square:
O O
O | OO | OO|
O | OO | OO|
Now if only one of the parents had a phenotype of O, then the man's genotype would be BO, or OB however you want to say it.
The punnett square would look like this:
B O
A | AB | AO |
B | BB | BO |
The genotype percentages would be
25% AB
25% AO
25% BB
25% BO
The phenotype percentages would be
25% AB
25% A
50% B

Answer 4

Looks like the traveling salesman has been busy.

If, on the other hand, you want to know about crossing AB with OO, half of the offspring will be heterozygous for type B.