ChildrenProbability puzzles require you to weigh all the possibilities and pick the most likely outcome.
The chances of a mother giving birth to a son compared with a daughter are 55%-45% (This is true in the real world due to a higher male infant mortality rate although the percent might be closer together depending on the type of country. 1st world, 3rd world - more males are born than females)
In a family of four children, what are the odds a mother will have 2 boys and a girl? AnswerI've listed all the possibilities b = boy g = girlThe chance of a child being male/female is independent, but the chance of having a certain order is just the probability multiplied by each other. Because one child doesn't matter; the desired scenarios are any with either 3 boys 1 girl or 2 girls 2 boys. I've marked with an X the desired outcomes, and at the end I have the probability of each occurrence. Simply add the probabilities together for each desired case! (as an eg of the calculation, bbgg is 0.55*0.55*0.45*0.45 which is the same answer as ggbb/ bgbg) b bbb x 0.09150625 b bbg x 0.07486875 b bgb x 0.07486875 b bgg x 0.06125625 b gbb x 0.07486875 b gbg x 0.06125625 b ggb x 0.06125625 b ggg x 0.05011875 g bbb x 0.07486875 g bbg x 0.06125625 g bgb x 0.06125625 g bgg x 0.05011875 g gbb x 0.06125625 g gbg x 0.05011875 g ggb x 0.05011875 g ggg x 0.04100625 Answer is 0.6670125 or approx 2/3 (As a check all the probabilities should sum 1) Hide What Next?
Tweet
See another brain teaser just like this one... Or, just get a random brain teaser If you become a registered user you can vote on this brain teaser, keep track of which ones you have seen, and even make your own. Back to Top |
