John and martha are contemplating having children, but john’s brother has galactosemia (an autosomal recessive disease) and martha’s great-grandmother also had galactosemia. martha has a sister who has three children, none of whom have galactosemia. what is the probability that john and martha’s first child will have galactosemia

As the question states,

John's brother has Galactosemia which states that his parents were both the carriers.

Therefore, the chances for the John to have the disease is = 2/3

Now,

Martha's great-grandmother also had the disease that means her children definitely carried the disease means probability of 1.

Now, one of those children married with a person.

So,

Probability for the child to have disease will be = 1/2

Now, again the child's child (Martha) probability for having the disease is = 1/2.

Therefore,

The total probability for Martha's first child to be diagnosed with Galactosemia will be,

(Here, we assumed that the child has the disease therefore, the probability was taken to be = 1/4.)

Hence, the probability for the first child to have Galactosemia is

step-by-step explanation:

the answer is 89 d

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