Computing joint probabilities in a Bayesian network

[puppydog]

Homework Statement

Homework Equations

The Attempt at a Solution

For part A I solved for P(B|JC) = P(B,JC)/P(JC)
For part B I am thinking P(B|!JC, MC) = P(B, !JC, MC) / P(!JC, MC)
For part C I am thinking P(JC|MC) = P(JC, MC)/P(MC)

Am I on track with these equations? Especially for part c? How do I compute P(JC, MC)?

 

[RUber]

The probability that john calls and mary calls can be found by examining all cases:
Burgled --> Alarm --> John calls =A1
Burgled --> Alarm --> Mary calls=A2
Not burgled --> Alarm --> John calls =B1
Not burgled --> Alarm --> Mary calls =B2
Burgled --> No Alarm --> John might call, but Mary won't =C1
Not Burgled --> No Alarm --> John might call, but Mary won't =D1
edit: P(JC & MC) = A1*A2/p(Burgled + Alarm) + B1*B2/p(Not burgled + alarm) + C1*0/p(burgled and no alarm) + D1*0/p(not burgled and no alarm)
P(MC) = A2+B2+0+0
P(JC) = A1+B1+C1+D1