Final answer:
The students were at the location for 1 hour and 45 minutes, as calculated by subtracting the arrival time from the departure time.
Step-by-step explanation:
If a group of students arrived somewhere at 3:30 pm and left at 5:15 pm, we can calculate the time they were there by subtracting the start time from the end time. Subtracting the hours: 5 pm minus 3 pm gives us 2 hours. Then, subtracting the minutes: 15 minutes minus 30 minutes gives us a negative number, so we need to adjust our hours by subtracting one hour and adding 60 minutes to the minutes part: 1 hour plus (60 + 15 - 30) minutes equals 1 hour plus 45 minutes. This means the students were there for a total of 1 hour and 45 minutes.