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Time duRATion

The time taken to finish an activity is called its duration. Some activities can be

completed in minutes and some in hours. If we know the starting time and finishing
time of an activity, we can find its duration.

example 1. Garima left for school at 7:20 a.m. and reached school at 7:50 a.m. How
much time did Garima take to reach school?

Solution. Duration from 7:20 a.m. to 7:30 a.m. = 10 minutes

Duration from 7:30 a.m. to 7:50 a.m. = 20 minutes

Total duration = 10 minutes + 20 minutes = 30 minutes

Thus, Garima took 30 minutes to reach school.

example 2. A bus left Ghaziabad at 5:40 p.m. and reached Delhi at 6:25 p.m. How

much time did the bus take to reach Delhi from Ghaziabad?
Solution. Duration from 5:40 p.m. to 6:00 p.m. = 20 minutes

Duration from 6:00 p.m. to 6:25 p.m. = 25 minutes

Total duration = 20 minutes + 25 minutes = 45 minutes

Thus, the bus took 45 minutes to reach Delhi from Ghaziabad.

example 3. Deepak’s school starts at 8:10 a.m. and ends at 1:40 p.m. How long does

the school work?
Solution. We find the duration from 8:10 a.m. to 1:40 p.m. as shown below:

Duration from 8:10 a.m. to 9:00 a.m. = 50 minutes

Duration from 9:00 a.m. to 1:00 p.m. = 4 hours

Duration from 1:00 p.m. to 1:40 p.m. = 40 minutes

Total time duration = 4 hours 90 minutes
4 hours 90 minutes = 4 hours + 60 minutes + 30 minutes

= 4 hours + 1 hour + 30 minutes
= 5 hours + 30 minutes

So, the school works for 5 hours 30 minutes. 1 hour = 60 minutes

To Find the Finishing Time

If we know the starting time and the duration of an activity, we can find its finishing

time.

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