It is not possible to answer the question because:
3 out of 7
Since the probability of having a son is about 1/2, the probability of the first 4 children being boys is about (1/2)4.
1:1
50/50
It depends on the couples' genes. Also, at present the probability of a girls is approx 0.48
3 out of 7
It is always 50/50.
Since the probability of having a son is about 1/2, the probability of the first 4 children being boys is about (1/2)4.
1:1
50/50
It depends on the couples' genes. Also, at present the probability of a girls is approx 0.48
In a family with four children, the probability of having four boys is 1 in 16.
These events are independent; so the probability of a girl is 0.5.
1/8
1/8?
Assuming the chances of having a boy and having a girl are equal (50/50), there are 4 possible outcomes from having 2 children. BOY-BOY, or GIRL-GIRL, or BOY-GIRL, or GIRL-BOY. Since each outcome is of equal probability it means there's a 25% chance the first will be a girl and the second will be a boy.
The probability of a boy is still 0.5 no matter how many prior children there are.