A school principal, his wife, and three other teachers are to be seated in a row. The principal and his wife must sit next to each other. Find the number of ways this can be done.

Discrete MathematicsPermutationsCombinatoricsCounting
2025/3/19

1. Problem Description

A school principal, his wife, and three other teachers are to be seated in a row. The principal and his wife must sit next to each other. Find the number of ways this can be done.

2. Solution Steps

There are 5 people in total: the principal, his wife, and three other teachers. Since the principal and his wife must sit together, we can consider them as a single unit.
Let's denote the principal as P, his wife as W, and the three teachers as T1, T2, and T

3. We can consider the principal and his wife as a single entity (PW or WP).

So, we have 4 entities to arrange: (PW), T1, T2, T

3. These 4 entities can be arranged in $4!$ ways.

4!=4×3×2×1=244! = 4 \times 3 \times 2 \times 1 = 24
However, the principal and his wife can switch places (PW or WP), so we must multiply by

2. The number of ways to arrange the principal and his wife is $2! = 2 \times 1 = 2$.

Therefore, the total number of arrangements is 4!×2!4! \times 2!.
4!×2!=24×2=484! \times 2! = 24 \times 2 = 48

3. Final Answer

The number of ways to seat the principal, his wife, and three other teachers such that the principal and his wife sit next to each other is 48.

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