2007-07-09 21:42:13 · 9 answers · asked by coleman57 1 in Science & Mathematics ➔ Biology
Not sure, but if both parents are healthy normal folks, with Mothers have the correct XX chromosomes and Fathers having XY chromosomes, then probably...
.5^ 9?
2007-07-09 21:46:28 · answer #1 · answered by bagtack 2 · 0⤊ 0⤋
I agree with the people who said it's (1/2)^9. Here's why.
Mom is XX. Dad is XY. Their possible offspring on a Punnett square are XX, XX, XY, XY. Two of the four possibilities are male. That's 1/2 chance that a child will be male.
In probability if you say "and" it means to multiply.
If the 9 babies are all boys, that means the first one is a boy AND the second one is a boy AND the third one is a boy AND ...
Chance of the first one being a boy is 1/2 AND chance of second one being a boy is 1/2 AND ...
1/2 * 1/2 * 1/2 * 1/2 * 1/2 * 1/2 * 1/2 * 1/2 * 1/2 = _____
2007-07-10 04:54:09 · answer #2 · answered by ecolink 7 · 0⤊ 0⤋
The male to female birth ratio is not 1 to 1. The answers above all assumed there was an equal chance of a boy being born as of a girl.
The source I quote below shows the sex ratios for most countries of the world. In the USA, for example, the ratio is 1.05 male births for every female birth. This means 1.05/(1.05+1)=1.05/2.05=0.5122 = 51.22% of babies born in the USA are male, NOT 50.00%.
If we take 9 random births, say the next 9 babies born in the USA, then the probability that all are males is 0.5122^9, or about 0.24%.
Genetic experts might argue that if the question was for a particular family then after a few boys in a row it might show that the father and mother or their environment is making it more likely than normal that the next baby will again be a boy.
But for the general population, in the USA, the answer is about 0.24%.
2007-07-10 05:18:12 · answer #3 · answered by Aiyah 3 · 0⤊ 0⤋
One half raised to the power 9 or 1/512
2007-07-10 04:47:04 · answer #4 · answered by Dulce D 2 · 0⤊ 0⤋
It's (1/2)^9 = 1/512 or about .00195.
2007-07-10 04:47:27 · answer #5 · answered by Escuerdo 3 · 0⤊ 0⤋
there is always a 50/50 chance are getting either a girl or boy.
the probability is 1/152 which is 0.0019531% chance
to figure it out just use a tree diagram
if there is 1 baby: 0.5
if there is 2 babies:0.25
if there is 3 babies:0.3333....etc
2007-07-14 02:45:19 · answer #6 · answered by Anonymous · 0⤊ 0⤋
(1/2)^9 = 1/512
=0.00195.
2007-07-10 04:50:57 · answer #7 · answered by sugarNspice 3 · 0⤊ 0⤋
there's a 50/50 chance that any baby will be a certain sex..I would say probaby rather rare that all would be boys..but eh..it could happen.
2007-07-10 04:59:48 · answer #8 · answered by ~~*Paradise Dreams*~~ 6 · 0⤊ 0⤋
its 5o-50 chance.
2007-07-14 03:48:12 · answer #9 · answered by 123(nick)123 2 · 0⤊ 0⤋