How are you using P(A\B)? Do you mean A not B or A given B?
In either case you are mistaken about the value unless that is what P(A\B).
Let A and B be events with P(A) = 2/5, P(B) = 1/2, P(AnB) = 3/20. Calculate the
following probabilities.
i) P(Ac) (means probabilty of Not A)
ii) P(A U B)
iii) P(Ac n B)
iv) P(B\A)
I know:
1) P(Ac)= 1-2/5= 3/5
2)P(A U B)= 2/5+1/2-3/20 = 3/4
But i am stuck on
iii) P(Ac n B)
iv) P(B\A)
Can anyone help me please