Chapter 12 - Data Analysis and Probability - 12-8 Probability of Compound Events - Practice and Problem-Solving Exercises - Page 768: 11

$\frac{1}{2}$

Looking at the spinner, there is one 3 and five red sections, out of 10 sections. However, we must take into account that the 3 is a red section. P(3 or red) = P(3) + P(red) - P(3 and red) = $\frac{1}{10}+\frac{5}{10} - \frac{1}{10} = \frac{5}{10} = \frac{1}{2}$