Q.If $P(A) = 0.6$ for an event $A$, find $P(A')$, the probability of 'not $A$'.

[!TLDR] Apply the complement rule $P(A')=1-P(A)$. …

By the complement rule, derived from $A \cup A' = S$ and $A \cap A' = \phi$ together with Axioms 2 and 3, $P(A') = 1 - P(A)$. Substituting $P(A) = 0.6$: $P(A') = 1 - 0.6 = 0.4$. As a c …

Subtract the given probability from $1$ using $P(A')=1-P(A)$, and verify t …

A common mistake is subtracting from the wrong total (e.g. from $100$ instead of $1$ when the probability is given as a decim …