A colour blind man marries a woman with normal sight who has no history of colour blindness in her family. What is the probability of their grandson being colour blind ?

A \(Nil\)
B \(0.25\)
C \(0.5\)
D \(1\)

Verified Solution

Answer & Solution

Correct Answer

(B) \(0.25\)

Step-by-step Solution

Detailed explanation

(b) : When a colour blind man \((X^cY)\) marries a normal woman \((XX)\), all of their daughters are carriers and all of their sons are normal, as shown in following figure: When the carrier daughter \((XX^c)\) is married to a normal man, the probability of their son being colour blind is \(0.25\), as shown in following figure:From above crosses, it is clear that the probability of occurrence of colour blindness in the grandson of a colour blind man and a normal woman is \(0.25\).

Apply the relevant identity from the chapter and substitute the values established in the previous step, keeping the original constraint in view.

Use the simplified expression to isolate the unknown, then plug the result back into the question setup to confirm the working is internally consistent.

Cross-check against a boundary or limiting case. Both the dimensional balance and the qualitative behaviour at the extreme should agree with the candidate answer.

Combine the steps above to identify the correct option. The remaining choices each fail at least one of the consistency, dimensional, or boundary checks.

Same subject

Explore more questions on app

From NEET

Explore more questions on app