In a pack of six chocolate drinks every carton is supposed to have a straw, but it is missing with probability $1/3$, with probability $1/3$ it is broken, with probability $1/3$ it is in perfect condition. Let $A$ be the event 'At least one straw is missing and at least one is in perfect condition'.
Question: Find a suitable probability space, formulate $A$ set-theoretically and find $P(A)$.
My ideas:
$\Omega:=\{1,2,3\}^6$ and $\mathcal{F}:=2^{\Omega}$
Where
$1:=$ "Straw missing"
$2:=$ "Straw broken"
$3:=$ "Straw in perfect condition"
$A:=\{\omega \in \Omega:\exists i,j \in \{1,2,3,4,5,6\}$ while $i \neq j$ and $\omega_{i}=1,\omega_{j}=3\}$
I think until this point I am correct. But I am struggling to find $P(A)$:
It may to be easier to look at $A^{c}:=$At most one straw is missing or at most one is in perfect condition. But I cannot come up with anything adequate.
I've though of something:
$P(A)=1-P(A^{c})=1-((\frac{1}{3})^{6}+\frac{6!}{5!1!}(\frac{1}{3})^{6}+\frac{6!}{5!1!}(\frac{1}{3})^{6})=\frac{716}{729}$
It is easier to compute $A^c$, which is that either no straws are missing or none are in perfect condition. There are $2^6$ ways you can have no straws missing, because each must be either broken or perfect. There are also $2^6$ ways you cam have no straws perfect. We have counted all broken in both cases, so $|A^c|=2\cdot 2^6-1=127$. The probability of $A$ is then $1-\frac {127}{3^6}$