b$)$ Describe the general procedure for construction of a Belief Network. Consider

$10$

the following Bayesian network. A$,$ B$,$ C$,$ and D are Boolean random variables. If we know that $A$ is true, what is the probability of $D$ being true?

$P(B|A)=0\mathrm{.}2$

$P(B|notA)=0.$

$C(A)=0\mathrm{.}7$

$C(notA)=0\mathrm{.}25$

$P(D|B^{{?}^{?}}C)=0\mathrm{.}3$

$P(D|B^{{?}^{?}}$notC$)=0\mathrm{.}25$

$P(D|not{B}^{{?}^{?}}C)=0\mathrm{.}1$

$P(D|not{B}^{{?}^{?}}$notC$)=0\mathrm{.}35$