question_answer

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)  1                    

B)  Nil           

C)  0.25                            

D)  0.5          

Correct Answer: C

Solution :

The daughters of this couple will have normal eye sight and carrier, if one of the carrier daughters marries a normal eyed man. Only 25 per cent of the grand son will be colour-blind. Hence, the correct option is [c].