Answer: the theoretical probability of winning a medium prize at the duck pond= 1/5 or 0.2.
Explanation:
Given: The total number of ducks in the pond =65
The number of ducks marked as medium-prize winners=13
Now, the probability of of winning a medium prize at the duck pond is given by:-

Hence, the theoretical probability of winning a medium prize at the duck pond= 1/5 or 0.2.