Answer
$\dfrac{5}{8}$ or $62.5\%$
Work Step by Step
Use the formula for not mutually exclusive events to find the probability of the events happening at the same time.
The formula is $P(A$ $or$ $B)=P(A)+P(B)-P(A$ $and$ $B)$.
We are given $P(A)=\dfrac{1}{2},$ $P(B)=\dfrac{1}{4},$ and $P(A$ $and$ $B)=\dfrac{1}{8}$.
Plug the values into the formula:
$P(A$ $or$ $B)$ = $\dfrac{1}{2}+\dfrac{1}{4}-\dfrac{1}{8}$
$P(A$ $or$ $B)$ = $\dfrac{4}{8}+\dfrac{2}{8}-\dfrac{1}{8}$
$P(A$ $or$ $B)$ = $\dfrac{5}{8}=62.5\%$
