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Practice THEME 2
Measurement and Geometry

4 Time

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SMART NOTES

1. Correlation between 12-hour system and Example:
24-hour system. The duration between 1430 hours and
Example: 1930 hours on the next day.
Write 1440 hours in the 12-hour system. 1430 2400 1930
4 4 0 hours hours hours
1
– 1 2 0 0 0000 hours
9 hours 19 hours
2 4 0 30 minutes 30 minutes
1440 hours = 2:40 p.m. Hours Minutes
Example: 4 23 0 0 60
2
Write 10:50 p.m. in the 24-hour system. – 1 4 3 0
0 5 5 9 3 0
1
+ 1 2 0 0
2 2 5 5 9 hours 30 minutes + 19 hours 30 minutes
= 29 hours
10:55 p.m. = 2255 hours
3. Time estimation involving hours and minutes
2. Duration of time involving the units hours and based on reference set.
minutes in the 24 hours Example:
Example: Fill a pail of water.
The duration of time between 1810 hours and
2140 hours.
Method 1
1810 1910 2010 2110 2140
hours hours hours hours hours
9:15 a.m.
3 hours 30 minutes 3 minutes
Method 2 9:18 a.m.
Hours Minutes
1 4 0 3 hours 30 minutes Estimated time to fi ll 3 pails
2
– 1 8 1 0 = 3 × 3 minutes
3 3 0 = 9 minutes

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