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From the image, there are two mathematical problems visible. Let's focus on each:

### Problem 3:
The question asks about the probability of getting a queue number that is an even number or a multiple of 3. The queue numbers range from 1 to 20.

We need to find the number of favorable outcomes where the queue number is either:
1. An even number (2, 4, 6, 8, 10, 12, 14, 16, 18, 20).
2. A multiple of 3 (3, 6, 9, 12, 15, 18).

Notice that the numbers 6, 12, and 18 are both even and multiples of 3, so we don't double-count these. 

- Even numbers: 10 numbers (2, 4, 6, 8, 10, 12, 14, 16, 18, 20)
- Multiples of 3: 6 numbers (3, 6, 9, 12, 15, 18)
- Common numbers (multiples of 3 and even): 3 numbers (6, 12, 18)

Using the inclusion-exclusion principle, the total favorable outcomes are:
\[ 10 + 6 - 3 = 13 \]

The probability is the number of favorable outcomes over the total number of outcomes (which is 20):
\[
\text{Probability} = \frac{13}{20}
\]
Thus, the answer is **C. \( \frac{13}{20} \)**.

---

### Problem 4:
This problem involves probability regarding extracurricular activities. We are given that out of 100 students:
- 60 students participate in basketball extracurricular activities.
- 50 students participate in futsal extracurricular activities.
- There are 10 students who participate in both.

We need to find the probability that a randomly selected student from these 100 students participates in either basketball or futsal.

Using the inclusion-exclusion principle:
- Total students involved in either activity is:
\[
60 + 50 - 10 = 100
\]
This means that 100 students are involved in at least one activity, so the probability of selecting one involved in either is:
\[
\text{Probability} = \frac{100}{100} = 1
\]
Thus, the answer is **A. 60%**.

---

Would you like to dive deeper into any of the concepts or have further questions?

Here are 5 related questions for more practice:
1. What is the probability of getting a number that is both a multiple of 5 and an even number in a range from 1 to 30?
2. How would the probability change if there were 200 students and only 80 participated in basketball?
3. Can the inclusion-exclusion principle be applied to three sets? If so, how?
4. What if there were 12 students involved in both activities, how would the answer in problem 4 change?
5. What is the probability of getting an odd number that is not a multiple of 3 between 1 and 20?

**Tip:** When solving probability problems, always check for overlaps (common elements) between the sets to avoid double-counting!

What is the probability of getting a queue number that is an even number or a multiple of 3 in the range 1 to 20, and what is the probability that a randomly selected student from a group of 100 participates in basketball or futsal extracurricular activities?

Explore how to calculate the probability of selecting a queue number that is an even number or a multiple of 3 from a range of 1 to 20, and the probability that a student participates in either basketball or futsal extracurricular activities, using the inclusion-exclusion principle. Suitable for students in Grades 9-11.

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