What is wrong with the expression PA PA bar 05 Choose the

What is wrong with the expression P(A) + P(A bar) = 0.5? Choose the correct answer below.

Solution

P ( A ) + P ( A \' ) is same as Probability of A happening and Probability of A not happening.

The total probability of A has to be equal 1, because the event can either happen or not happen.

So,

P (A) + P(A\')

= P (A) + [ 1 - P(A) ]

= 1 ( and not 0.5)

Hope this helps. Ask if you have any doubts.