Let's go through each part of the problem step by step.
### a. Write the set \( P \) in listing method.
The set \( U = \{1, 2, 3, \ldots, 16\} \) contains the numbers from 1 to 16. The set \( P \) is defined as the set of composite numbers \( x \) such that \( x \leq 13 \).
The composite numbers less than or equal to 13 are:
- 4 (2 × 2)
- 6 (2 × 3)
- 8 (2 × 4)
- 9 (3 × 3)
- 10 (2 × 5)
- 12 (3 × 4)
- 14 (2 × 7) (not included since it is greater than 13)
- 15 (3 × 5) (not included since it is greater than 13)
Thus, the set \( P \) in listing method is:
\[
P = \{4, 6, 8, 9, 10, 12\}
\]
### b. Find \( P \cap Q \cap R \).
We have:
- \( P = \{4, 6, 8, 9, 10, 12\} \)
- \( Q = \{2, 3, 6, 9, 12, 15\} \)
- \( R = \{2, 4, 6, 12, 14, 16\} \)
Now, we will find the intersections:
1. **Find \( P \cap Q \)**:
\[
P \cap Q = \{4, 6, 8, 9, 10, 12\} \cap \{2, 3, 6, 9, 12, 15\} = \{6, 9, 12\}
\]
2. **Find \( P \cap R \)**:
\[
P \cap R = \{4, 6, 8, 9, 10, 12\} \cap \{2, 4, 6, 12, 14, 16\} = \{4, 6, 12\}
\]
3. **Find \( P \cap Q \cap R \)**:
\[
P \cap Q \cap R = \{6, 9, 12\} \cap \{4, 6, 12\} = \{6, 12\}
\]
Thus, the intersection \( P \cap Q \cap R \) is:
\[
P \cap Q \cap R = \{6, 12\}
\]
### c. Show the given information in a Venn-Diagram.
To create a Venn diagram, we will represent the three sets \( P \), \( Q \), and \( R \) as overlapping circles.
1. **Circle for \( P \)** will contain: \( 4, 6, 8, 9, 10, 12 \)
2. **Circle for \( Q \)** will contain: \( 2, 3, 6, 9, 12, 15 \)
3. **Circle for \( R \)** will contain: \( 2, 4, 6, 12, 14, 16 \)
**Overlapping areas**:
- \( P \cap Q \): \( 6, 9, 12 \)
- \( P \cap R \): \( 4, 6, 12 \)
- \( Q \cap R \): \( 2 \) (not in \( P \))
- \( P \cap Q \cap R \): \( 6, 12 \)
### d. Verify the relation:
\[
n(P) = n_0(P) + n_0(P \cap Q) + n_0(P \cap R) + n(P \cap Q \cap R)
\]
Where:
- \( n(P) \) is the number of elements in \( P \).
- \( n_0(P) \) is the number of elements in \( P \) only.
- \( n_0(P \cap Q) \) is the number of elements in \( P \cap Q \) only.
- \( n_0(P \cap R) \) is the number of elements in \( P \cap R \) only.
- \( n(P \cap Q \cap R) \) is the number of elements in \( P \cap Q \cap R \).
Calculating the sizes:
- \( n(P) =
(a) \( P = \{4, 6, 8, 9, 10, 12\} \)
(b) \( P \cap Q \cap R = \{6, 12\} \)
(c) Venn diagram representation of sets \( P \), \( Q \), and \( R \) with their intersections.
(d) The relation \( n(P) = n_0(P) + n_0(P \cap Q) + n_0(P \cap R) + n(P \cap Q \cap R) \) is verified with the given sets.