1. **State the problem:** Mr. Johnson's class has 13 students with an A average, 10 with a B average, 4 with a C average, and 3 with a D average. We want to find the probability that a randomly selected student has either a B or C average. 2. **Formula for probability of simple events:** $$P(E) = \frac{\text{Number of favorable outcomes}}{\text{Total number of outcomes}}$$ 3. **Identify favorable outcomes:** The favorable outcomes are students with a B or C average. Number of students with B average = 10 Number of students with C average = 4 Total favorable outcomes = 10 + 4 = 14 4. **Calculate total number of students:** Total students = 13 + 10 + 4 + 3 = 30 5. **Calculate the probability:** $$P(\text{B or C}) = \frac{14}{30}$$ 6. **Simplify the fraction:** $$\frac{14}{30} = \frac{\cancel{14}}{\cancel{30}} = \frac{7}{15}$$ 7. **Final answer:** The probability that Mr. Johnson will select a student with either a B or C average is $\frac{7}{15}$.