Awoman with normal brca alleles has a child with a man who has one mutated brca1 allele. what is the probability that the child will have a mutated brca1 allele?

50%

Explanation:

According to the given information, the woman has normal BRCA alleles while the man carries one copy of the mutated BRCA allele (BRCA1). A diploid organism such as human beings can have two BRCA alleles. A child gets one BRCA allele from the mother and the other from the father.

The child of the couple would get one normal allele from the woman. However, with respect to the BRCA allele, the man would form two types of gametes in equal proportion. The 50% of his gametes would have the mutated BRCA1 allele while the rest 50% would carry the normal BRCA allele. Therefore, the man can transmit either normal or mutated BRCA allele to the child. So, there are 50% chances for the child to get the mutated allele.