Question 1038184
Pr(A or B) = Pr(A) + Pr(B) - Pr(A and B) = 0.4 + 0.5 - 0.1 = 0.8


However this includes the case where both A and B occur. To account for this, we have to subtract 0.1 again.


Pr(A xor B) = 0.8 - 0.1 = 0.7


So the probability that A or B occurs, but not both, is 0.7.