Conversion Of Time
In this article, we will be learning about the conversion of time and the 24-hour clock. The lesson objectives are:
Topic Recap:
Conversion of Time
We can express time in hours and minutes to minutes.
Example 1:
- \(1 \text{ h } = 60 \text{ min}\)
- \(\begin{align}\\ 2 \text{ h } &= 2 \times 60 \text{ min}\\ &= 120 \text{ min} \end{align}\)
- \(\begin{align}\\ 3 \text{ h } 20 \text{ min } &= 180 \text{ min }+ 20 \text{ min }\\ &= 200 \text{ min } \end{align}\)
We can also express time in minutes to hours and minutes.
Example 2:
- \(180 \text{ min } = 3 \text{ h } 0 \text{ min }\)
- \(\begin{align}\\ 400 \text{ min } &= 360 \text{ min }+ 40 \text{ min }\\ &= 6 \text{ h } 40 \text{ min } \end{align}\)
1. Conversion Of Time
\(1 \text{ minute } = 60 \text{ seconds}\)
To express time from minutes to seconds, we multiply the number of minutes by 60.
To express time from seconds to minutes, we divide the number of seconds by 60.
\(1 \text{ hour} = 60 \text{ minutes}\)
To express from hours to minutes, we multiply the number of hours by 60.
To express from minutes to hours, we divide the number of minutes by 60.
Question 1:
Express the following time in seconds.
- \(\displaystyle{2} \text{ min} =\) __________ s
- \(\displaystyle{2} \text{ h} =\) __________ s
- \(\displaystyle{\frac {1}{4}} \text{ h} =\) __________ s
Solution:
A. \(\begin{align}\\ 2 \text{ min } &= 2 \times 60\\ &= 120 \text{ s} \end{align}\)
Answer:
120 s
B. \(\begin{align}\\[2ex] 2 \text{ h } &= 2 \times 60\\ &= 120 \times 60\\ &= 7200 \text{ s} \end{align}\)
Answer:
7200 s
C. \(\displaystyle{\frac {1}{4} \text{ h}}\)
\(\because\) \(1 \text{ h}\) = 60 min
\(\therefore\) \(\displaystyle{\frac {1}{4} \text{ h}}\) = 60 min ÷ 4 = 15 min
\(\therefore\) 15 min = 15 × 60 s = 900 s
Answer:
900 s
Question 2:
Express the following time in seconds.
5 min = __________ s
Solution:
5 min = 5 × 60 s
= 300 s
Answer:
300 s
Question 3:
Express the following time in seconds.
45 min = __________ s
Solution:
45 min = 45 × 60 s
= 45 × 6 × 10
= 2700 s
Answer:
2700 s
Question 4:
Express the following time in seconds.
\(1\frac {1}{2}\) h = __________ s
Solution:
1 h = 3600 s
\(\frac {1}{2}\)h = 30 min
= 30 × 60
= 1800 s
\(1\frac {1}{2}\) h = 3600 s + 1800 s
= 5400 s
Answer:
5400 s
Question 5:
Express the following time in minutes or hours and minutes.
- 180 s = __________ min
- 3000 s = __________ min
- 4500 s = __________ h __________ min
Solution:
- 180 s = 180 ÷ 60
= 3 min
Answer:
3 min
- 3000 s = 3000 ÷ 60
= 50 min
Answer:
50 min
- 4500 s = 4500 ÷ 60
= 75 min
= 1 h 15 min
OR
1 h = 3600s
4500 s - 3600 s = 900 s
= 900 ÷ 60
= 15 min
Hence, 4500 s = 1 h 15 min
Answer:
1 h 15 min
Question 6:
Express the following time in minutes or hours and minutes.
120 s = __________ min
Solution:
120 s
= 120 ÷ 60
= 2 min
Answer:
2 min
Question 7:
Express the following time in minutes or hours and minutes.
300 s = ___________ min
Solution:
300 s
= 300 ÷ 60
= 5 min
Answer:
5 min
Watch Our Video Lesson!
2. 24-Hour Clock Format
In the 24-hour clock, there is no need to add suffixes like am or pm. It is written in 4 digits, where the first two digits represent the hour and the last two digits represent the minutes.
Time from midnight to noon:
12-h clock = 12:00 am to 11:59 am
24-h clock = 00 00 to 11 59
Time from noon to midnight:
12-h clock = 12:00 pm to 11:59 pm
24-h clock = 12 00 to 23 59
Example:
12-h clock |
24-h clock |
---|---|
5:30 am |
05:30 |
5:30 pm |
17:30 |
10:30 am |
10:30 |
10:30 pm |
22:30 |
12:00 pm |
12:00 |
12:00 am |
00:00 |
Question 1:
Express the following time in 24-hour clock.
- 8:50 am = __________
- 12:20 am = __________
- 9:10 pm = __________
Solution:
a) 8:50 am = 08 50
Answer:
08 50
b) 12:20 am = 00 20
Answer:
00 20
c) 9:10 pm = 21 10
Answer:
21 10
Question 2:
Express the following time in 24-hour clock.
2:35 am = __________
Solution:
2:35 am = 02 35
Answer:
02 35
Question 3:
Express the following time in 24-hour clock.
11:15 pm = __________
Solution:
11:15 pm = 23 15
Answer:
23 15
Question 4:
Which of the following clocks shows the time 19:15?
Solution:
19 15 is 7:15 pm in the evening.
Answer:
(4)
Question 5:
Express the following time in 12-hour clock.
- 03 30 = __________
- 12 50 = __________
- 17 45 = __________
Solution:
- 03 30 = 3:30 am
- 12 50 = 12:50 pm
- 17 45 = 5:45 pm
Question 6:
Express the following time in 12-hour clock.
00 10 = __________
Solution:
00 10 = 12:10 am
Answer:
12:10 am
Question 7:
Express the following time in 12-hour clock.
20 15 = __________
Solution:
20 15 = 8:15 pm
Answer:
8:15 pm
Continue Learning | |
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Multiplication | Whole Numbers |
Multiplication And Division | Decimals |
Model Drawing Strategy | Division |
Fractions | Factors And Multiples |
Area And Perimeter 1 | Line Graphs |
Time |