maths
posted by Claire .
Hi Can anyone help please:
Suppose that the births of boys and girls can be modelled by rollling a fair die with 27 faces, 14 of which represent a boy and 13 represent a girl.
1. Using this model, choose the option that is closest to the probability that a couple who continue to have children until they have a boy will have exactly 3 children? I answered this as 0.1394, Is this correct?
2. Using this model, choose the option that is closest to the probability that a couple who continue to have children until they have a boy will have more than 3 children?
3. Using this model, choose the option that is closest to the probability that, in a family with five children, the 1st, 3rd and 5th are girls, while the 2nd, and 4th are boys? I got 0.03456, is this correct?
Options given for questions 1 to 3 are: A=0.0300, B=0.1116 C=0.1202 D=0.1295 E=0.1394 F=0.3221 G= 0.5469 H=06324
really could do with some help please

1. for this to happen the sequence must be GGB which has a prob of (13/27)^2(14/27) = .1202
2. must be GGGB or GGGGB or GGGGGB ....
= (13/27)^3(14/27) + (13/27)^4(14/27) + ...
this the sum of an infinite geometric series where
a = (13/27)^3(14/27) and r = 13/27
sum = a/(1r) = .057877/(1  13/27) = .1116
3. prob (GBGBG) = (13/27)^3(14/27)^2 , the order in which we multiply these does not matter
= .0300
Respond to this Question
Similar Questions

odds of...
Does anyone know the odds of having Two girls as children as opposed to two males or one male and one female? 
maths
1. A die labelled A has one face marked 1, one face marked 2 and the other four faces marked 3. A die labelled B has four faces marked 2 and two faces marked 3. The dice A and B are thrown. Calculate the probability is 5. I got 18/36 … 
Math
In a family with two children, what are the probabilities of the following outcomes, assuming that the birth of boys and girls is equally likely? 
Math
In a family with two children, what are the probabilities of the following outcomes, assuming that the birth of boys and girls is equally likely? 
math
in a family with two children, what are the probabilities of two boys, the first is a girl the second is a boy, neither is a girl, at least one girl, assuming that the birth of boys and girls is equally likely. 
maths
Hi Can anyone help please: Suppose that the births of boys and girls can be modelled by rollling a fair die with 27 faces, 14 of which represent a boy and 13 represent a girl. 1. Using this model, choose the option that is closest … 
math
Assuming boy and girl babies are equally likely, find the probability that it would take a) at least three births to obtain two girls b) at least four births to obtain two girls c) at least five births to obtain two girls 
math
Assuming boy and girl babies are equally likely, find the probability that it would take a) at least three births to obtain two girls b) at least four births to obtain two girls c) at least five births to obtain two girls 
Maths
Question: total of 40 students in class, boys number is double of the girls number. How many boys & girls in the class? 
Maths
Question: total of 40 students in class, boys number is double of the girls number. How many boys & girls in the class?