If $P(B) = 0.8$, then $P(B^c)$ can be found using the complement rule. The complement rule states that:

$P(B^c) = 1 - P(B)$

Substituting the given value:

$P(B^c) = 1 - 0.8 = 0.2$

So, $P(B^c) = 0.2$.

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Would you like further details or have any questions? Here are some related questions:

1. What does $P(B^c)$ represent in probability theory?
2. If $P(A) = 0.7$, how would you find $P(A^c)$?
3. How does the complement rule help in probability problems?
4. What is the probability of $P(B^c)$ if $P(B)$ is $0.5$?
5. How can we interpret the complement of an event in real-world scenarios?

Tip: Remember, the complement of an event represents all the outcomes in the sample space that are not part of the original event.