# Imat 2022 q29 & 2017 q35

Hi, can anyone help me solve these questions please?
In the first question, I got “3 in 8” by solving 1/2 * 3/4 = 3/8 because it’s asking a boy without the condition.
And then I solved the statement 1 of the other question with the same approach and got 1/2 * 1/4 = 1/8 (12.5%). However, the answer is 25%. I need some explanation on this!!

A mother and a father, neither of whom has cystic fibrosis, conceive a child who has the condition.

What is the likelihood that the same parents will have another child who is a boy without cystic fibrosis?

A. 1 in 4
B. 3 in 4
C. 1 in 2
D. 3 in 8
E. 1 in 8

A male child has haemophilia. Neither parent has the condition. The parents have a second child.
Which of the following statements could be correct about this family?
1 There is a 25% chance that the second child is a boy with haemophilia.
2 There is a 75% chance that the second child does not show the condition.
3 There is a 50% chance that the mother is a carrier.
[Assume no other mutations.]
A 1 and 2 only
B 2 only
C 3 only
D 1 only
E 2 and 3 only

You can’t do the same approach in the second question because hemophilia is X linked recessive
So Xx crossed with xY gives the offfspring:
XX Xx XY xY
P(boy)=1/2
P(boy with hemophilia)=1/2
Ptotal=1/4

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