Final answer:
The trout population in the Delaware River decreased by 8,500, which is a 24.29% decrease from the original population of 35,000.
Step-by-step explanation:
To express the change in the trout population in the Delaware River as a percent, we first need to calculate the difference in the number of trout. The population decreased from 35,000 to 26,500, which is a difference of 35,000 - 26,500 = 8,500 trout. To find the percentage decrease, we divide the difference by the original amount and then multiply by 100:
Percentage decrease = (Difference / Original Amount) × 100%
Percentage decrease = (8,500 / 35,000) × 100%
Percentage decrease = (0.2428571429) × 100%
Percentage decrease = 24.29%
Therefore, the trout population in the Delaware River has experienced a 24.29% decrease.