At the Beijing Olympics, Maria and Tânia, the women, and Juan and David, the men, all athletes, sat at a square table. Each of them practices a different sport: swimming, volleyball, gymnastics, and athletics. They were seated as follows:

(a) The one who practices swimming was to the left of Maria.

(b) The one who practices gymnastics was opposite Juan.

(c) Tânia and David sat next to each other.

(d) A woman sat next to the one who practices volleyball.

Which of the athletes practices athletics?
To start, we choose a place for Maria.

![](https://cdn.mathpix.com/cropped/2024_05_01_dbce7bc2a200e234c3e2g-27.jpg?height=171&width=249&top_left_y=1031&top_left_x=903)

(a) The person who practices swimming is to the left of Maria. Therefore, we can only have the configuration below.

![](https://cdn.mathpix.com/cropped/2024_05_01_dbce7bc2a200e234c3e2g-27.jpg?height=206&width=246&top_left_y=1567&top_left_x=945)

(b) The person who practices gymnastics is in front of Juan. There are two unique possibilities: Maria practices gymnastics or Maria does not practice gymnastics.

Maria practices gymnastics

![](https://cdn.mathpix.com/cropped/2024_05_01_dbce7bc2a200e234c3e2g-27.jpg?height=230&width=415&top_left_y=2140&top_left_x=432)

Maria does not practice gymnastics

![](https://cdn.mathpix.com/cropped/2024_05_01_dbce7bc2a200e234c3e2g-27.jpg?height=287&width=290&top_left_y=2106&top_left_x=1400)

(c) Since Tânia and David sat together, only the second option from the previous item - Maria does not practice gymnastics - can satisfy this condition. It generates the following two possibilities:

![](https://cdn.mathpix.com/cropped/2024_05_01_dbce7bc2a200e234c3e2g-28.jpg?height=370&width=1264&top_left_y=444&top_left_x=431)

(d) Since a woman sat next to the person who practices volleyball, the second option from the previous item is correct, and we have:

![](https://cdn.mathpix.com/cropped/2024_05_01_dbce7bc2a200e234c3e2g-28.jpg?height=369&width=1350&top_left_y=970&top_left_x=385)

Therefore, David or Maria practices athletics.