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find-time-intervals-using-addition-and-subtraction-effectively

🚀 Measurement of time intervals involves understanding how to calculate the duration between two points in time. This can be done using addition and subtraction. For example, if an event starts at 2:00 PM and ends at 3:30 PM, we can find the time interval by subtracting the start time from the end time. This concept is essential for scheduling, planning, and understanding how long activities take.

Theory Explanation

Understanding Time Intervals

A time interval is the difference between two times. To find the time interval, we can either add or subtract time. When we subtract, we find out how much time has passed. When we add, we can find out what time it will be after a certain duration.

Using Subtraction to Find Time Intervals

To find the time interval using subtraction, we take the end time and subtract the start time. Make sure both times are in the same format (AM/PM) and convert if necessary. If the minutes of the end time are less than the start time, we need to borrow an hour from the hours.

Using Addition to Find Future Times

To find out what time it will be after a certain duration, we can add the duration to the start time. Again, ensure that the minutes and hours are correctly calculated, and convert if the minutes exceed 60.

Key Points

  • 🎯 A time interval is the difference between two times.
  • 🎯 Use subtraction to find how much time has passed.
  • 🎯 Use addition to find what time it will be after a certain duration.
  • 🎯 Always ensure times are in the same format (AM/PM).
  • 🎯 Convert minutes to hours if they exceed 60.

Examples:💡

If a movie starts at 1:15 PM and ends at 3:00 PM, how long is the movie?

Solution:

Step 1: Subtract the start time from the end time: 3:00 PM - 1:15 PM.

Step 2: Convert the times to minutes: 3:00 PM is 180 minutes and 1:15 PM is 75 minutes.

Step 3: Now subtract: 180 - 75 = 105 minutes.

Step 4: Convert 105 minutes back to hours and minutes: 105 minutes is 1 hour and 45 minutes.

Common Mistakes

  • Mistake: Students often forget to convert minutes when they exceed 60.

    Correction: Always check if the minutes are more than 60 and convert them to hours.

  • Mistake: Students may not align AM/PM correctly when subtracting times.

    Correction: Ensure both times are in the same format before performing any calculations.

  • Mistake: Students sometimes add instead of subtracting when finding time intervals.

    Correction: Remember to subtract the start time from the end time to find the interval.

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