To find the number of child tickets sold at the water park, you can calculate 65% of the total number of tickets sold, which is 100.
First, convert the percentage to a decimal:
\[ 65% = 0.65 \]
Now, multiply the total number of tickets by this decimal:
\[ 0.65 \times 100 = 65 \]
Thus, the park sold 65 child tickets.