There are 2 children in a family.What is the probability of having at least one girl?

or:There are 2 children in a family.What is the probability of having at least one girl?or:There are four possible combinations of two sexes. Two of

or:There are 2 children in a family.What is the probability of having at least one girl?

or:There are four possible combinations of two sexes. Two of them qualify, so the probability is 50%.

or:\"You may have heard that if a couple have two children, both of the same gender, say girls, their chances of conceiving a third female baby are higher than conceiving a male. This idea has lived on for centuries but it\u2019s simply a myth. Another myth related to gender are that men are more \u201cmanly\u201d if they produce a line of boys and that women are more \u201cfeminine\u201d if they produce all girls.With each pregnancy, a couple has a 50% chance of conceiving either a boy or a girl. It\u2019s no different than flipping a coin two times in a row and getting tails each time; the third time, the likelihood of getting tails is still 50%. The previous two coin flips won\u2019t influence the outcome of the third. With each pregnancy, a couple has the same 50% chance of conceiving a girl.It\u2019s human nature to believe that somehow a cause underlies such events, but not true in the game of chance or in gender selection.Although numerous people can attest to examples of families with only girls or only boys \u2014 sometimes six or 10!\u2014 semen samples from the fathers in these cases reveal a 50:50 ratio of male to female sperm. Remember, all semen contains approximately 50% of female-carrying (X) sperm cells and 50% male-carrying (Y) sperm cells.\"

or:b := boyg := girlLet's build our event-space. What do we know? There are two different sexes (b, g) , and for all practical purposes the probabilities P for the 1st child are: P(b) = 0.5, P(g) = 0.5 .The probabilities for the 2nd child are also: P(b) = 0.5, P(g) = 0.5 .The question refers to the outcome of both independent events. For both children we get this event space S(E):S(E) = {b,g} \u00d7 {b,g} = { (b,b), (b,g), (g,b), (g,g) }, each with a probability of 0.25.The condition \"At least one girl\" matches 3 states of the event space. The probability of having at least one girl is then 0.75 or 75%.

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