3/8
Assuming probability of having a boy is P(B) = 1/2, and of having a girl is P(G) = 1/2,the probability of having 3 boys for 4 kids (with out regard to the girl to be the first,second, third or fourth kid) is;P(3B1G) = 4C3 [P(B)]4 = 4 (1/2)4 = 0.250 = 25%The factor 4 comes because there are 4 possibilities for the order in which the girl cancome out.
If we consider there is a 50% chance for having a boy and 50% for having a girl*, there is : - 12,5% chance of having no boys; - 37,5% chance of having 1 boy; - 37,5% chance of having 2 boys; - 12,5% chance of having 3 boys. Therefore, there is 50% chance of having at least two boys. *The odds are more like 51% for having a boy and 49% for having a girl, but it doesn't really matters.
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.
There is only one girl out of 12 students so the probability that the girl is selected is 1/12.
Assuming the probability of having a boy is 1/2, and that the probabilities are independent: Probability of 1 girl and 12 boys = (1/2)13 * 13 = 0.001587..., which is around 1/630
3/8
Assuming probability of having a boy is P(B) = 1/2, and of having a girl is P(G) = 1/2,the probability of having 3 boys for 4 kids (with out regard to the girl to be the first,second, third or fourth kid) is;P(3B1G) = 4C3 [P(B)]4 = 4 (1/2)4 = 0.250 = 25%The factor 4 comes because there are 4 possibilities for the order in which the girl cancome out.
In a family with four children, the probability of having four boys is 1 in 16.
1/8
If we consider there is a 50% chance for having a boy and 50% for having a girl*, there is : - 12,5% chance of having no boys; - 37,5% chance of having 1 boy; - 37,5% chance of having 2 boys; - 12,5% chance of having 3 boys. Therefore, there is 50% chance of having at least two boys. *The odds are more like 51% for having a boy and 49% for having a girl, but it doesn't really matters.
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.
The probability of having a girl versus a boy is 1/2 because there is two things you have a chance of getting and you can only get one or the other.
Assuming that the probability of having a baby girl is 1/2 and that of having a baby boy is 1/2, the probability of having 3 baby girls in a row is (1/2)(1/2)(1/2)=1/8.
1/4
There is only one girl out of 12 students so the probability that the girl is selected is 1/12.
Assuming that having boys and girls are equally likely, then the probability is 1/8. * * * * * You also need to assume that the children's genders are independent. They are NOT and depend on the parents' ages and genes.