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solve-problems-involving-start-and-end-times-systematically

🚀 Measurement of time intervals involves calculating the duration between a start time and an end time. This concept is essential for understanding how long an event lasts, which is a common situation in daily life. To solve problems involving start and end times, we need to follow a systematic approach that includes identifying the start and end times, converting them into a consistent format (if necessary), and then calculating the difference between them.

Theory Explanation

Identifying Start and End Times

The first step is to clearly identify the start time and the end time of the event. Make sure to note whether the times are in the same format (AM/PM or 24-hour clock). If they are not, convert them to the same format before proceeding.

Calculating the Time Difference

Once you have the start and end times, subtract the start time from the end time to find the duration. If the end time is earlier than the start time, you may need to adjust by adding 12 hours (for AM/PM) or converting to the next day.

Expressing the Result

Finally, express the result in hours and minutes. If the result is in minutes, convert it to hours if necessary.

Key Points

  • 🎯 Always identify the start and end times clearly.
  • 🎯 Convert times to the same format if needed.
  • 🎯 Subtract the start time from the end time to find the duration.
  • 🎯 Be mindful of AM/PM distinctions when calculating time intervals.
  • 🎯 Express the final answer in hours and minutes.

Examples:💡

A movie starts at 2:30 PM and ends at 4:15 PM. How long is the movie?

Solution:

Step 1: Identify the start time (2:30 PM) and end time (4:15 PM).

Step 2: Convert both times to a 24-hour format: 2:30 PM is 14:30 and 4:15 PM is 16:15.

Step 3: Subtract the start time from the end time: 16:15 - 14:30.

Step 4: Calculate the difference: 16:15 - 14:30 = 1 hour and 45 minutes.

Step 5: The movie lasts for 1 hour and 45 minutes.

Common Mistakes

  • Mistake: Students often forget to convert AM/PM times to a 24-hour format before calculating.

    Correction: Always convert times to the same format before performing any calculations.

  • Mistake: Students may subtract incorrectly, especially when the end time is on the next day.

    Correction: If the end time is earlier than the start time, remember to adjust by adding 12 hours or consider it as the next day.

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