Answer: There were 304 children and 89 adults at the public pool on that hot summer day.
Step-by-step explanation:
Let's say the total number of people at the pool that day is x + y = 393
The total cost of admission for all the people is $678.50
The cost for each child's admission is $1.50 and the cost for each adult's admission is $2.50
We can use this information to set up two equations:
x + y = 393 (Total number of people)
1.5x + 2.5y = 678.5 (Total cost of admission)
Now we can use the first equation to solve for one of the variables. For example, we can solve for y:
y = 393 - x
We can substitute this value of y into the second equation:
1.5x + 2.5(393 - x) = 678.5
We can then solve this equation for x:
1.5x + 982.5 - 2.5x = 678.5
-x = -304
x = 304
This means that there were 304 children at the pool that day. We can use the first equation to find the number of adults:
x + y = 393
304 + y = 393
y = 393 - 304
y = 89
Therefore, there were 304 children and 89 adults at the public pool on that hot summer day.