What is the probability that her third child will be a girl? Explain your reasoning.
2007-09-20 18:29:56 · 9 answers · asked by Anonymous in Science & Mathematics ➔ Biology
50%..the same as ANY other time.
Reason: In females, all eggs are X..so this has no role in determining sex.
In males, meiosis, which produces the sperm, will produce 50% X ( "female") sperm and 50% Y ( male) sperm. This means there are technically the same numbers of male and female sperm present and therefore there is the SAME chance that a male (Y) will fertilse the egg as it is for a femaler (X) sperm to fertilise the sperm.
Its the same for flipping a coin....the chande you will get heads and tails, for EACH flip is the SAME as it was for the previous.
2007-09-20 18:39:20 · answer #1 · answered by mareeclara 7 · 1⤊ 0⤋
Mathmatically there is really four choices. The third choice is the baby being a hermaphrodite and the fourth choice is there is more than one baby. You have to factor those two other factors into the equation. Another factor is if she used assisted reproductive technology (which then create the starting point of the equation of just 54% being just one child). In Massachusetts during 2005, 1 out of 38 births was a multiple birth. If that is a common percentage across othre areas, then there is a 2.63% chance of a multiple birth. I also come across a bit where 4% of all live births are hermaphrodites.
At birth there is a historical 1.05 male births to 1 female birth.
So I'm going to guess about 46% chance that it will be a girl. That leaves a 53% that the birth will involve a boy, a multiple birth or a hermaphrodite. I already factored in a chance of one of the multiple births being a hermaphrodite. I didn't factor in still births, just live births.
2007-09-20 19:34:48 · answer #2 · answered by gregory_dittman 7 · 0⤊ 0⤋
Usually it is 50%, since each child being born is an independant event. However, perhaps the Y chromosome is experiencing meiotic drive or some other factor is favoring sperm that contain a Y. I would still put my money on 50/50, and keep in mind chances are(probibly) that this woman has had several fertalized eggs that were girls that did not implant correctly, or perhaps a miscarrage(More pregnancies fail than go to term). Those two boys were just the ones that made it through.
2007-09-20 18:41:47 · answer #3 · answered by Kenlas 3 · 0⤊ 0⤋
probability that the third child is a girl is still 1/2
the probability for having either a boy or girl for every birth is 1/2 because "technically" there are ONLY two possibilities.
2007-09-20 18:37:48 · answer #4 · answered by Anonymous · 0⤊ 0⤋
1/2, the male gives either the X or the Y chromosome from his sex allele. the female gives either X or X. GIving u 4 combinations: X,X, X,X, X,Y, X,Y. XX will be a female. so its 1/2 no matter how many kids she had before.
2007-09-20 19:31:57 · answer #5 · answered by bobrowra 2 · 0⤊ 0⤋
50% The fact that she had two sons before has effect on the current pregnancy.
2007-09-20 18:37:05 · answer #6 · answered by andy2210 2 · 0⤊ 0⤋
it all depends on the x and y chromosomes of the father....but looking at it without that the chance is 50/50
2007-09-20 18:39:40 · answer #7 · answered by lazerangel99 4 · 0⤊ 0⤋
It depends. My bro has 3 girls...he wanted a boy..but oh well...
2007-09-20 18:38:01 · answer #8 · answered by ♥♥Pro♥♥ 6 · 0⤊ 0⤋
its the same 50% probability . are you retarded or something?
2007-09-20 20:47:57 · answer #9 · answered by cybervanig2000 2 · 0⤊ 0⤋