Suppose we have two dice one fair and one tha brings $6$ with quintuple probability.Find the probability to throw randomly one die and show $6$ Suppose we have two dice one fair and one that brings $6$ with quintuple probability than the other numbers.We get a die randomly and we throw it.What is the probability to have $6$?In the same problem if we know that we have $6$ what is the probability that we have throwed the second die?
Any ideas for these  parts especially the second one?

HINT: put a name at each random variable. By example $D\in\{d1,d2\}$ is the random variable of picking one dice or the other, and $T\in\{1,2,...,6\}$ is the random variable to get some value on the throw.
And we know that 
$$\Pr[T=6|D=d1]=1/6\quad\text{ and }\quad\Pr[T=6|D=d2]=1/2$$
Now we want to evaluate
1) $\Pr[T=6]$, and
2) $\Pr[D=d2|T=6]$
