Answer
$\dfrac{1}{2}$
Work Step by Step
We know that $\text{probability}=\dfrac{\text{number of favorable outcomes}}{\text{number of all outcomes}}=\dfrac{n(F)}{n(S)}.$
There are $5$ odd numbers in the sample space so $5$ outcomes favor the event $F$.
There are a total of $10$ possible outcomes.
Hence,
$P(F)=\dfrac{5}{10}=\dfrac{1}{2}$