Exercise 12.4
A. Write 12 hour clock time for the following.
1. 0530 hours = 5:30 a.m.
2. 1015 hours = _____________
3. 2350 hours = _____________
4. 0610 hours = _____________
5. 2020 hours = _____________
6. 1325 hours = _____________
B. Write 24 hour clock time for the following.
1. 3:15 p.m. = 1515 hours
2. 8:55 a.m. = _____________
3. 9:45 p.m. = _____________
4. 6:30 a.m. = _____________
5. 8:53 p.m. = _____________
6. 12:50 a.m. = _____________
C. Match the following.
1. 4:34 p.m. | 1715 hours | ||
2. 5:15 p.m. | 2200 hours | ||
3. 2:56 a.m. | 0950 hours | ||
4. 8 a.m. | 1634 hours | ||
5. 10 p.m. | 0256 hours | ||
6. 9:50 a.m. | 0800 hours |
Conversion of time
The seconds hand is the fastest hand of the clock. Observe that it moves very fast, hopping from one number to other.
Seconds hand makes one complete round of the clock in 1 minute.
Time taken by the second's hand to move from one small division to another is called second.
There are 60 equal divisions on a clock face.
Hence,
1 minute = 60 seconds
And 1 hour = 60 minutes
To convert:
- Minute to second, multiply by 60.
- Second to minute, divide by 60.
To convert:
- Hour to minute, multiply by 60.
- Minute to hour, divide by 60.
Example 1: Convert 5 minutes 30 seconds to seconds.
5 minutes 30 seconds | = | 5 ⨯ 60 seconds + 30 seconds |
= | 300 seconds + 30 seconds | |
= | 330 seconds |
Example 2: Convert 6 hours 55 minutes to minutes.
6 hours 55 minutes | = | 6 ⨯ 60 minutes + 55 minutes |
= | 360 minutes + 55 minutes | |
= | 415 minutes. |
Example 3: Convert 300 seconds to minutes and seconds.
300 seconds ÷ 60 = 5 minutes
Example 4: : Convert 330 seconds to minutes and seconds.
330 seconds ÷ 60
Q = 5 and R = 30
330 seconds to minutes and seconds = 5 minutes and 30 seconds.
Example 5: Convert 145 minute to hours and minutes.
145 minutes ÷ 60
Q = 2 and R = 25
Therefore, 145 minutes = 2 hours 25 minutes.
Think and Answer
A. Hemant works as a guard at The National Zoological Park, Delhi. Here is his daily routine. Rewrite the sentences by writing the time in a.m. and p.m.
1) He gets up in the morning at 05:00 hours.
2) He has his breakfast at 06:15 hours.
3) He reaches the zoo around 07:00 hours.
4) Opens all the doors at 07:30 hours.
5) Guards the zoo gate from 08:00 hours to 16:00 hours.
6) Locks all the doors at 16:15 hours.
7) Takes a round of the zoo to ensure that no one is left behind at 16:30 hours.
8) Reaches home around 18:00 hours.
Exercise 12.5
A. Convert into seconds.
1. 6 minutes | _____________________________________ | ||
2. 11 minutes | _____________________________________ | ||
3. 4 minutes 20 seconds | _____________________________________ | ||
4. 15 minutes 10 seconds | _____________________________________ | ||
5. 30 minutes | _____________________________________ | ||
6. 7 hour 30 minutes | _____________________________________ |
B. Convert into minutes.
1. 12 hours | _____________________________________ | ||
2. 2 hour 10 minutes | _____________________________________ | ||
3. 3 hours 15 minutes | _____________________________________ | ||
4. 4 hours 35 minutes | _____________________________________ | ||
5. 5 hours 50 minutes | _____________________________________ | ||
6. 10 hours 10 minutes | _____________________________________ |
C. Convert into minutes and seconds.
1. 180 seconds | _____________________________________ | ||
2. 350 seconds | _____________________________________ | ||
3. 570 seconds | _____________________________________ | ||
4. 800 seconds | _____________________________________ | ||
5. 1800 seconds | _____________________________________ | ||
6. 3630 seconds | _____________________________________ |
D. Convert into hours and minutes.
1. 80 minutes | _____________________________________ | ||
2. 420 minutes | _____________________________________ | ||
3. 570 minutes | _____________________________________ | ||
4. 880 minutes | _____________________________________ | ||
5. 1200 minutes | _____________________________________ | ||
6. 3600 minutes | _____________________________________ |