To find the ratio of the number of students sitting on the bleachers to the number of students sitting on the floor, we can express this mathematically.
The number of students sitting on the bleachers is 7, and the number of students sitting on the floor is 36. The ratio can be written as:
\[ \text{Ratio} = \frac{\text{Students on Bleachers}}{\text{Students on Floor}} = \frac{7}{36} \]
To express this ratio using a colon, we write it as:
\[ \text{Ratio} = 7 : 36 \]
Thus, the ratio of the number of students sitting on the bleachers to the number of students sitting on the floor is 7 : 36.