Maths Olympiad Prep

Track / Stage 6 / 304 of 400 #1304 of 1964

Problem 1304

National olympiad, first round
Combinatorics Difficulty 6.6 Find the answer

Four couples go ballroom dancing one evening. Their first names are Henry, Peter, Louis, Roger, Elizabeth, Jeanne, Mary, and Anne. If Henry's wife is not dancing with her husband (but with Elizabeth's husband), Roger and Anne are not dancing, Peter is playing the trumpet, and Mary is playing the piano, and Anne's husband is not Peter, who is Roger's wife?

Pick one

Official solution

1. Identify the dancers and non-dancers:
- Henry's wife is dancing with Elizabeth's husband.
- Roger and Anne are not dancing.
- Peter is playing the trumpet.
- Mary is playing the piano.
- Anne's husband is not Peter.

2. Determine Elizabeth's husband:
- Since Elizabeth's husband is dancing, he cannot be Roger (not dancing), Peter (playing the trumpet), or Henry (his wife is dancing with Elizabeth's husband).
- Therefore, Elizabeth's husband must be Louis.

3. Determine Henry's wife:
- Henry's wife is dancing with Elizabeth's husband (Louis).
- Henry's wife cannot be Anne (not dancing), Mary (playing the piano), or Elizabeth (married to Louis).
- Therefore, Henry's wife must be Jeanne.

4. Determine Anne's husband:
- Anne's husband is not Peter.
- Since Louis and Henry already have their partners (Elizabeth and Jeanne, respectively), the only remaining option is Roger.

5. Determine Roger's wife:
- Since Roger is Anne's husband, Roger's wife is Anne.

Thus, the answer is Anne\boxed{\text{Anne}}.

Source: NuminaMath-1.5, licensed Apache-2.0. Statement and solution reproduced as published; topic, difficulty and ordering added by this site.