Page 177 - Revised Maths Wisdom Class - 3

Time and Calendar 175

a.m. and p.m.

An interval of a complete day and night is of 24 hours. 12 hours make the whole duration

of a day and remaining 12 hours make the duration of the night.

● 12 o’clock at night is called midnight and 12 o’clock in the day is called noon.

● The time between midnight and noon is denoted by a.m. (anti meridiem).

● The time between noon and midnight is denoted by p.m. (post meridiem).

Time Duration

Duration of an activity can be measured in both minutes and hours. Duration of activities
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such as reciting your morning prayer, bathing, dressing up, brushing teeth, etc., can be

measured in minutes. Duration of a journey, sports event, etc. are measured in hours.

Let's Try

Example: The basketball tournament began at 10:40 a.m. It fi nished aft er
3 hours from start. What time did the game fi nish?

11 12 1 11 12 1 11 12 1 11 12 1
10 2 10 2 10 2 10 2
9 3 1 h 9 3 1 h 9 3 1 h 9 3
8 4 8 4 8 4 8 4
7 6 5 7 6 5 7 6 5 7 6 5

10:40 a.m. 11:40 a.m. 12:40 p.m. 1:40 p.m.

The game fi nished at 1:40 p.m.

Conversion of Time

We also measure time of longer duration in days, weeks, months and years.

1 week = 7 days
1 month = 30/31 days
1 year = 365 days
1 day = 24 hours 1 year = 12 months
1 hour = 60 minutes 1 year = 52 weeks