One parent has blood type O, and the other has blood type Bi. What is the chance that they have a child that is blood type O?

50%

Explanation:

Draw a Punnett square to solve this problem (see photo).

Blood type O has two recessive alleles, represented by two lowercase “i”s.

Blood type Bi has a dominant allele shown by capital i with superscript B and a recessive allele “i”.

In the result, two boxes are “IB i” (for blood type Bi) and two boxes are “i i” (for blood type O).

The chance of having a child with blood type O is:

2/4 = 1/2 = 50%

Therefore, the chance of having a child with blood type O is 50%.