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Measure - Calculating time intervals and durations

Grade 3IGCSE

Review the key concepts, formulae, and examples before starting your quiz.

🔑Concepts

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Reading time on analog and digital clocks (12-hour format).

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Understanding AM (Ante Meridiem - before noon) and PM (Post Meridiem - after noon).

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Calculating duration: Finding the amount of time that has passed between a 'Start Time' and an 'End Time'.

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The Jump Method: Using a timeline to jump to the next hour to simplify calculations.

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Converting basic units of time: hours to minutes and minutes to seconds.

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Calendar skills: Understanding days in a week and months in a year.

📐Formulae

1 hour=60 minutes1 \text{ hour} = 60 \text{ minutes}

1 minute=60 seconds1 \text{ minute} = 60 \text{ seconds}

1 day=24 hours1 \text{ day} = 24 \text{ hours}

Duration=End Time−Start Time\text{Duration} = \text{End Time} - \text{Start Time}

💡Examples

Problem 1:

A cartoon starts at 4:15 PM and ends at 5:00 PM. How long was the cartoon?

Solution:

45 minutes

Explanation:

Start at 4:15 PM. Count forward to the next whole hour (5:00 PM). 60−15=4560 - 15 = 45. So, the duration is 45 minutes.

Problem 2:

School starts at 8:30 AM. If the first lesson lasts 1 hour and 15 minutes, what time does it end?

Solution:

9:45 AM

Explanation:

First, add the hour: 8:30 AM+1 hour=9:30 AM8:30 \text{ AM} + 1 \text{ hour} = 9:30 \text{ AM}. Next, add the minutes: 9:30 AM+15 minutes=9:45 AM9:30 \text{ AM} + 15 \text{ minutes} = 9:45 \text{ AM}.

Problem 3:

A train journey takes 130 minutes. Express this time in hours and minutes.

Solution:

2 hours and 10 minutes

Explanation:

Since 1 hour=60 minutes1 \text{ hour} = 60 \text{ minutes}, 2 hours=120 minutes2 \text{ hours} = 120 \text{ minutes}. Subtract 120 from 130 (130−120=10130 - 120 = 10). This leaves 2 hours and 10 minutes.

Problem 4:

How many minutes are there in 3 hours?

Solution:

180 minutes

Explanation:

Multiply the number of hours by 60: 3×60=1803 \times 60 = 180 minutes.