Answer:
9
Step-by-step explanation:
There are 9 students who spend the following number of hours in a typical day on the computer.
3,3,5,7,7,9,9,9,12
The mode is the number that is of the highest frequency in any given set of values.
The mode number of hours is the highest number of hours spent on the computer.
The number 9 occured the most times. Therefore the mode hour is 9