Everyday maths 1 (Wales)
Everyday maths 1 (Wales)

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6.1 Calculate time difference

You may need to work out differences in time, e.g. to work out the length of a TV programme or journey time.

There are different ways to work out the difference in time. One of the easiest ways is to use the adding on method.

Example: Time difference by adding on

How long is it from 08:45 to 10:30?

Method

The start time is 08:45.

The number of minutes between 08:45 and the start of the next hour, 09:00, is 15 minutes.

The number of hours between 09:00 and 10:00 is one hour.

The number of minutes between 10:00 and 10:30 is 30 minutes.

So the time between 08:45 to 10:30 is:

15 minutes + 30 minutes + 1 hour = 1 hour 45 minutes

Now try the following activity.

Activity 21: Time difference

What is the length of time between the following times?

  1. 03:55 to 06:35
  2. 09:45 to 12:15
  3. 08:26 to 10:14
  4. 7:55 a.m. to 1:10 p.m.
  5. Midday to 15:50
  6. 3:15 am to midnight

Answer

  1. The start time is 03:55.

    The number of minutes between 03:55 and the start of the next hour, 04:00, is 5 minutes.

    The number of hours between 04:00 and 06:00 is two hours.

    The number of minutes between 06:00 and 06:35 is 35 minutes.

    So the time between 03:55 to 06:35 is:

    • 5 minutes + 35 minutes + 2 hours = 2 hours 40 minutes
  2. The start time is 09:45.

    The number of minutes between 09:45 and the start of the next hour, 10:00, is 15 minutes.

    The number of hours between 10:00 and 12:00 is two hours.

    The number of minutes between 12:00 and 12:15 is 15 minutes.

    So the time between 09:45 to 12:15 is:

    • 15 minutes + 15 minutes + 2 hours = 2 hours 30 minutes

Following the same method, you should have these answers for the other questions:

  1. 1 hour 48 minutes
  2. 5 hours 15 minutes
  3. 3 hours 50 minutes
  4. 20 hours 45 minutes

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