Solution:
The results for the event were:
Position
|
Country
|
Gold (First)
|
Brazil
|
Silver (Second)
|
Dominican Republic
|
Bronze (Third)
|
Equador
|
Fourth
|
Argentina
|
Fifth
|
Canada
|
Here is an explanation:
(I) Assume that the Argentinian got the gold. Then his statement that he wasn't last was true. This is a contradiction.
Assume that the Canadian got the gold. Then it follows that, the Brazilian spoke falsely, so he must have got the silver. The Dominican's statement that Equador got silver is false.
So, the Dominican who didn't get
a gold or the silver winner spoke falsely. This is a contradiction. So, the Canadian did NOT get the gold.
Assume that the Equadorian got gold. Then his statement that the Dominican didn't get gold is true. This is a contradiction.
Similarly, if the Dominican got gold then by his false statement the Equadorian didn't get silver. Thus, the Equadorian spoke the truth saying that the Dominican didn't get the gold. This is a contradiction.
Accordingly, the only possibility is that, the remaining individual - that is, the Brazilian - GOT the GOLD.
(II) Assume that the Argentinian got the silver. Then, his statement that he wasn't the last is true. This is a contradiction.
Assume that the Canadian got the silver. Then, the Dominican's statement is false. So the Dominican also won the silver. This is a contradiction.
Assume that the Equadorian got silver. Then his false statement implies that the Dominican got the gold. But, we have established before that the Brazilian got the gold.
This leads to a contradiction.
Accordingly, the remaining individual -- that is, the Dominican GOT the SILVER.
(III) None of these these three individuals: The Argentinian, the Canadian and the Equadorian got the gold or the silver. Therefore, each of their statements must be true.
In terms of true statements made by the Argentinian and the Canadian:
Argentina ended up behind Equador but, Argentina wasn't last (fifth position).
Since the Brazilian got the gold and the Dominican got the silver, the only possibility is: (Equador, Argentina) = (3,4), so that the Equadorian got the bronze and the Argentinian assumed the fourth position.
Accordingly, the remaining individual, that is, the Canadian, came in last (fifth position).