Elapsed time: The amount of time that passes between a start time and an end time.
Total time: The sum of multiple time periods.
- Identify the start time: 2:10 PM
- Identify the end time: 2:45 PM
- Subtract the start time from the end time
- Calculate: 2:45 PM - 2:10 PM = 35 minutes
Start time: 2:10 PM, End time: 2:45 PM
End minutes - Start minutes: 45 - 10 = 35 minutes
End hours - Start hours: 2 - 2 = 0 hours
0 hours and 35 minutes = 35 minutes
This is elapsed time - the duration between start and end times
The elapsed time is 35 minutes. This is the time Tom spent reading.
• Elapsed time: Measures the duration between two specific times
• Total time: Would be the sum of multiple activities
| Concept | Definition | Example |
|---|---|---|
| Elapsed Time | Duration between start and end times | 2:10 PM to 2:45 PM = 35 minutes |
| Total Time | Sum of multiple time periods | Reading: 35 min + Writing: 25 min = 60 min |
Total time: The sum of multiple time periods added together.
Elapsed time: The duration between a start and end time of a single event.
Jogging: 25 minutes, Swimming: 35 minutes
25 minutes + 35 minutes = 60 minutes
60 minutes = 1 hour
This is total time - the sum of multiple activities
The total time Lisa spent exercising is 1 hour (60 minutes).
• Total time: Add multiple time periods together
• Elapsed time: Would measure a single continuous event
| Activity | Duration | Cumulative Total |
|---|---|---|
| Jogging | 25 minutes | 25 minutes |
| Swimming | 35 minutes | 60 minutes (1 hour) |
Elapsed time: Duration between start and end times of a single event.
Total time: Sum of multiple time periods.
Start: 7:30 AM, End: 9:15 AM
Since 15 < 30, borrow: 9:15 becomes 8:75
Minutes: 75 - 30 = 45 minutes
Hours: 8 - 7 = 1 hour
Elapsed time: 1 hour 45 minutes
Activity 1: 45 minutes
Activity 2: 1 hour = 60 minutes
Activity 3: 30 minutes
Total: 45 + 60 + 30 = 135 minutes = 2 hours 15 minutes
Elapsed time (bus ride): 1 hour 45 minutes
Total time (activities): 2 hours 15 minutes
The elapsed time of the bus ride is 1 hour 45 minutes. The total time of all activities is 2 hours 15 minutes.
• Elapsed time: Measured between specific start and end times
• Total time: Sum of multiple separate time periods
| Event Type | Description | Calculation | Result |
|---|---|---|---|
| Elapsed Time (Bus) | Duration of single event | 9:15 - 7:30 = 1:45 | 1 hour 45 minutes |
| Total Time (Activities) | Sum of multiple events | 45 + 60 + 30 = 135 min | 2 hours 15 minutes |
Elapsed time: The amount of time that passes between a start time and an end time
Total time: The sum of multiple time periods added together
Start time: The time when an event begins
End time: The time when an event finishes
Duration: The length of time an event takes
- Identify start and end times: Locate them in the problem
- Check for borrowing: If end minutes < start minutes, borrow 1 hour
- Perform subtraction: Subtract minutes and hours separately
- Combine results: Express as hours and minutes
- Identify all time periods: List each activity duration
- Convert to same units: Make sure all times are in minutes or hours
- Perform addition: Add all time periods together
- Convert if needed: Change minutes to hours if necessary
• Elapsed time: Always involves a start and end time
• Total time: Always involves adding multiple time periods
• Conversion: 1 hour = 60 minutes
• Units: Keep all time measurements in the same units
Advanced comparison: Calculating both elapsed time for a single event and total time for multiple events.
Start: 6:45 PM, End: 9:20 PM
Since 20 < 45, borrow: 9:20 becomes 8:80
Minutes: 80 - 45 = 35 minutes
Hours: 8 - 6 = 2 hours
Elapsed time: 2 hours 35 minutes
Reading: 45 minutes
Writing: 1 hour = 60 minutes
Exercising: 30 minutes
Total: 45 + 60 + 30 = 135 minutes = 2 hours 15 minutes
Elapsed time (movie): 2 hours 35 minutes
Total time (other activities): 2 hours 15 minutes
The elapsed time of the movie is 2 hours 35 minutes. The total time of all other activities is 2 hours 15 minutes.
• Elapsed time: Single event duration calculation
• Total time: Multiple time periods addition
| Event Type | Details | Calculation | Result |
|---|---|---|---|
| Elapsed Time (Movie) | Start: 6:45 PM, End: 9:20 PM | 9:20 - 6:45 = 2:35 | 2 hours 35 minutes |
| Total Time (Other Activities) | Reading: 45 min, Writing: 60 min, Exercise: 30 min | 45 + 60 + 30 = 135 min | 2 hours 15 minutes |
Full day comparison: Calculating elapsed time across multiple hours and total time of multiple activities.
Start: 8:30 AM, End: 3:15 PM
Convert to 24-hour: Start: 8:30, End: 15:15
Since 15 < 30, borrow: 15:15 becomes 14:75
Minutes: 75 - 30 = 45 minutes
Hours: 14 - 8 = 6 hours
Elapsed time: 6 hours 45 minutes
Activity 1: 45 minutes
Activity 2: 1 hour 15 minutes = 75 minutes
Activity 3: 30 minutes
Activity 4: 50 minutes
Total: 45 + 75 + 30 + 50 = 200 minutes = 3 hours 20 minutes
Trip elapsed time: 6 hours 45 minutes = 405 minutes
Total activities: 3 hours 20 minutes = 200 minutes
Time not in activities: 405 - 200 = 205 minutes = 3 hours 25 minutes
The elapsed time of the entire trip is 6 hours 45 minutes. The total time of all activities is 3 hours 20 minutes. Time not spent in activities is 3 hours 25 minutes.
• Multi-hour elapsed time: Handle AM/PM conversion if needed
• Total time: Convert all to same units before adding
| Measurement | Calculation | Result | Notes |
|---|---|---|---|
| Elapsed Time (Trip) | 3:15 PM - 8:30 AM = 6:45 | 6 hours 45 minutes | Entire trip duration |
| Total Time (Activities) | 45 + 75 + 30 + 50 = 200 min | 3 hours 20 minutes | Sum of all activities |
| Time Not in Activities | 6:45 - 3:20 = 3:25 | 3 hours 25 minutes | Travel, breaks, etc. |
Elapsed time: The amount of time that passes between a start time and an end time
Total time: The sum of multiple time periods added together
Start time: The time when an event begins
End time: The time when an event finishes
Duration: The length of time an event takes
Time period: A specific amount of time for an activity
- Identify start and end times: Locate them in the problem
- Check for borrowing: If end minutes < start minutes, borrow 1 hour
- Perform subtraction: Subtract minutes and hours separately
- Combine results: Express as hours and minutes
- Identify all time periods: List each activity duration
- Convert to same units: Make sure all times are in minutes or hours
- Perform addition: Add all time periods together
- Convert if needed: Change minutes to hours if necessary
• Elapsed time formula: End time - Start time
• Total time formula: Sum of all time periods
• Borrowing rule: When end minutes < start minutes, borrow 1 hour (60 minutes)
• Unit conversion: 1 hour = 60 minutes
• Verification: Check if your answer makes sense in context
Questions & Answers
Question: How do I know if a problem is asking for elapsed time or total time?
Answer: Look for these clues in the problem:
- Elapsed time: Has a start time and end time for ONE event (e.g., "from 2:00 to 3:30")
- Total time: Mentions multiple activities or time periods to add together (e.g., "reading for 30 min, writing for 45 min")
Elapsed time uses subtraction, total time uses addition!
Question: Can elapsed time and total time ever be the same?
Answer: Yes, they can be the same in special cases! For example:
- If someone does only ONE activity, the elapsed time of that activity equals the total time spent
- If a 30-minute movie runs from 2:00 to 2:30, the elapsed time (30 min) equals the total time (30 min)
But generally, elapsed time measures one event while total time adds multiple events!
Question: What if I have to add hours and minutes? Like 1 hour 30 minutes + 45 minutes?
Answer: Convert everything to the same unit first! Here's how:
- 1 hour 30 minutes = 60 + 30 = 90 minutes
- 90 minutes + 45 minutes = 135 minutes
- Convert back: 135 minutes = 2 hours 15 minutes (since 120 min = 2 hours, 15 min remain)
Always convert to the same units before adding!