To determine the minimum number of adults that need to purchase a ticket, we begin by calculating the total revenue generated by the students.
Given that the cost of a student ticket is $3 and that 226 students purchased tickets, we can calculate the total revenue from student ticket sales as follows:
\[ \text{Revenue from students} = 226 \times 3 = 678 \text{ dollars} \]
Next, we need to find out how much more money is needed to reach the minimum goal of $1,500. We do this by subtracting the revenue from students from the total target:
\[ \text{Additional revenue needed} = 1500 - 678 = 822 \text{ dollars} \]
Now, let \( x \) represent the number of adult tickets sold. The price of an adult ticket is $5, so the revenue generated from adult ticket sales can be expressed as:
\[ \text{Revenue from adults} = 5x \]
We need this revenue from adults to be at least $822:
\[ 5x \geq 822 \]
To isolate \( x \), we divide both sides of the inequality by 5:
\[ x \geq \frac{822}{5} = 164.4 \]
Since \( x \) must be a whole number (as you cannot sell a fraction of a ticket), we round up to the nearest whole number:
\[ x \geq 165 \]
Therefore, the minimum number of adults that need to purchase a ticket is \( \boxed{165} \).