P(B) = 1 - P(B') = 1 - (7/12) = 5/12
P(A∩B)=P(A∩B′)/P(B′) × P(B)/1
Plugging values into the last equation we get:
P(A∩B)=1×12×5 / 6×7×12 = 542
Now we can make use of the following formula
P(A|B)=P(A∩B) / P(B)
by plugging in the values that we have found.
5/42 is the numerator and the denominator is 5/12.
The bottom (denominator) is P(B) which equals 5/12.
P(A|B)=5×12 / 42×5 = 6/210
6/210 = 2/7
p(a[b]) = 2/7
