Measurement - Reading 24-hour clocks and timetables

Grade 5IGCSE

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

🔑Concepts

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Understanding the difference between 12-hour (AM/PM) and 24-hour clock notation.

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Converting 12-hour time to 24-hour time: For PM times (except 12 PM), add 12 to the hours.

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Converting 24-hour time to 12-hour time: For hours 13 to 23, subtract 12 and add 'PM'.

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Midnight in 24-hour format is written as 00:00, and Midday is 12:00.

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Reading timetables involves tracking departure and arrival times across rows and columns.

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Calculating time intervals (duration) by counting forward from the start time to the end time.

📐Formulae

\text{24-hour Time (PM)} = \text{12-hour Time} + 12 \text{ hours}

\text{12-hour Time (from 13:00-23:59)} = \text{24-hour Time} - 12 \text{ hours}

\text{Time Interval} = \text{Arrival Time} - \text{Departure Time}

💡Examples

Problem 1:

Convert 3:45 PM into 24-hour clock format.

Solution:

15:45

Explanation:

3 + 12 = 15

Problem 2:

A train leaves Station A at 14:20 and arrives at Station B at 16:05. How long was the journey?

Solution:

1 hour and 45 minutes

Explanation:

Count from 14:20 to 15:20 (1 hour). Then count from 15:20 to 16:05 (45 minutes). Total duration = 1h 45m.

Problem 3:

A bus timetable shows a bus departing at 08:50 and taking 35 minutes to reach the destination. What is the arrival time in 24-hour format?

Solution:

09:25

Explanation:

Add 35 minutes to 08:50. Adding 10 minutes reaches 09:00. The remaining 25 minutes makes it 09:25.