Blood type probability

In humans, the ABO and Rh are under the control of autosomal genes. If two parents who are both A positive, produce a child who is type O negative, what is the probability their next child will be type O positive?

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Similar to the precious problem, here you have a child that is homozygous recessive for two genes, while parents are heterozygous (because they display different/dominant phenotype).

Once you work that out you get parental genotype AaBb (or any other abbreviations you choose). All you need to do now is a cross AaBb x AaBb and figure out the probability of the O+ve phenotype (genotype aaBb or aaBB).

Good Luck!

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