Question

If the couple has four girls, the probability of fifth being a male is
A) 50%
B) 25%
C) 75%
D) 100%

Answer 1

Hint:An analysis of hundreds of years of family trees shows that the genes of a man play a part in sons or daughters having him. Men inherit from their parents a propensity to have more sons or more daughters. This means that it is more likely for a man with many brothers to have sons, while a man with many sisters is more likely to have daughters.

Complete answer:
Sex determination, the establishment of an organism's sex, typically by the inheritance of certain genes generally clustered on a specific chromosome at the time of fertilisation. By regulating cellular metabolism and stimulating the production of hormones that activate the development of sexual glands or organs, this pattern impacts the development of the organism.The sex of a baby is determined at conception by its chromosome composition. An embryo will become a female with two X chromosomes, while an embryo will result in a boy with an X-Y combination. The Y chromosome carries a vital gene called SRY, which works on another gene called SOX9 to activate embryo test growth. For normal development of the testis, high levels of the SOX9 gene are needed.However, if there is any SOX9 behaviour disturbance and there are only low levels, a testis will not develop, resulting in a baby with a sex development disorder.Neither parent gets to make a call. Nearly everybody has around a 50% chance of having a boy and a 50% chance of having a child.
What we may claim is that the sperm of a father decides if a child is going to be a boy or a girl. A boy and half a girl would make up about half of his semen. The baby's sex depends on which sperm first gets to the egg.

FEMALE/MALE	X	Y
X	XX	XY
X	XX	XY

Thus the correct Answer is option (A) 50%.

Note :The presence of sex chromosomes in the genetic code establishes biological sex in healthy humans: a female is made of two X chromosomes (XX), while a boy is made of an X and a Y chromosome (XY). It is the presence or absence of the Y chromosome in a healthy human that separates boy from girl in this way.