p(n|ture) = 0.02 -> p(p|true) = 0.98
p(p|false) = 0.05
p(true) = 0.98 -> p(false) = 0.02
p(p,true) = p(p|true)*p(true) = 0.98*0.98 = 0.9604
p(p,false) = p(p|false)*p(false) = 0.05*0.02=0.001
-> p(p) = 0.9614
p(true|p) = p(p,true) / p(p)
= 0.9604/0.9605
= 0.9989