Time (Grade 5)
In Class 5, the topic of Time extends to advanced calculations involving 24-hour clock format, elapsed time, conversion between units of time, and word problems on schedules and durations.
You already know how to read a clock and tell time. Now you learn to calculate how much time passes between events, convert between hours, minutes, and seconds, and solve problems involving train and bus timetables.
Time is measured using standard units: seconds, minutes, hours, days, weeks, months, and years.
What is Time - Class 5 Maths (Time)?
Time (Grade 5) Formula
Elapsed Time = End Time − Start Time
24-Hour Clock:
| 12-Hour Format | 24-Hour Format |
|---|---|
| 12:00 midnight | 00:00 |
| 6:00 AM | 06:00 |
| 12:00 noon | 12:00 |
| 1:00 PM | 13:00 |
| 6:00 PM | 18:00 |
| 11:59 PM | 23:59 |
To convert PM time to 24-hour format: add 12 to the hour (except 12 PM stays as 12).
Solved Examples
Example 1: Example 1: Finding Elapsed Time
Problem: School starts at 8:15 AM and ends at 2:30 PM. How long is the school day?
Solution:
Step 1: From 8:15 AM to 12:15 PM = 4 hours
Step 2: From 12:15 PM to 2:15 PM = 2 hours
Step 3: From 2:15 PM to 2:30 PM = 15 minutes
Step 4: Total = 4 + 2 hours 15 minutes = 6 hours 15 minutes
Answer: The school day is 6 hours 15 minutes long.
Example 2: Example 2: Converting to 24-Hour Clock
Problem: Convert 4:45 PM to 24-hour format.
Solution:
Step 1: Since it is PM, add 12 to the hour: 4 + 12 = 16
Step 2: Keep the minutes: 45
Answer: 4:45 PM = 16:45
Example 3: Example 3: Converting Hours to Minutes
Problem: Convert 3 hours 25 minutes to minutes.
Solution:
Step 1: 3 hours = 3 × 60 = 180 minutes
Step 2: Total = 180 + 25 = 205 minutes
Answer: 3 hours 25 minutes = 205 minutes
Example 4: Example 4: Train Journey Problem
Problem: Ria's train departs at 09:30 and arrives at 14:15. How long is the journey?
Solution:
Step 1: From 09:30 to 14:30 = 5 hours
Step 2: But arrival is 14:15, which is 15 minutes before 14:30
Step 3: So duration = 5 hours − 15 minutes = 4 hours 45 minutes
Answer: The journey is 4 hours 45 minutes.
Example 5: Example 5: Adding Time
Problem: Aman starts studying at 5:40 PM. He studies for 2 hours 35 minutes. At what time does he finish?
Solution:
Step 1: 5:40 PM + 2 hours = 7:40 PM
Step 2: 7:40 PM + 35 minutes = 8:15 PM
Answer: Aman finishes at 8:15 PM.
Example 6: Example 6: Converting Minutes to Hours and Minutes
Problem: A movie is 155 minutes long. Express this in hours and minutes.
Solution:
Step 1: 155 ÷ 60 = 2 remainder 35
Step 2: So 155 minutes = 2 hours 35 minutes
Answer: 2 hours 35 minutes
Example 7: Example 7: Time Difference Across Midnight
Problem: Priya starts reading at 10:30 PM and stops at 1:15 AM. How long did she read?
Solution:
Step 1: From 10:30 PM to 12:00 midnight = 1 hour 30 minutes
Step 2: From 12:00 midnight to 1:15 AM = 1 hour 15 minutes
Step 3: Total = 1 hr 30 min + 1 hr 15 min = 2 hours 45 minutes
Answer: Priya read for 2 hours 45 minutes.
Example 8: Example 8: Converting Seconds
Problem: Convert 3,720 seconds to hours, minutes, and seconds.
Solution:
Step 1: 3,720 ÷ 60 = 62 minutes (0 seconds remain)
Step 2: 62 ÷ 60 = 1 hour 2 minutes
Answer: 3,720 seconds = 1 hour 2 minutes
Example 9: Example 9: Bus Timetable
Problem: Buses leave every 40 minutes. The first bus leaves at 06:20. At what time does the 4th bus leave?
Solution:
Step 1: After 3 intervals of 40 minutes: 3 × 40 = 120 minutes = 2 hours
Step 2: 06:20 + 2 hours = 08:20
Answer: The 4th bus leaves at 08:20.
Example 10: Example 10: Leap Year Problem
Problem: How many days are there from 1 January to 31 March in a leap year?
Solution:
Step 1: January = 31 days
Step 2: February in leap year = 29 days
Step 3: March = 31 days
Step 4: Total = 31 + 29 + 31 = 91 days
Answer: 91 days
Key Points to Remember
- 1 hour = 60 minutes, 1 minute = 60 seconds, 1 day = 24 hours.
- Use the 24-hour clock for timetables: PM time = hour + 12.
- Elapsed time = End time − Start time.
- When adding time, carry over: 60 minutes → 1 hour, 60 seconds → 1 minute.
- A leap year has 366 days (February has 29 days). A year divisible by 4 is usually a leap year.
- For time problems across midnight, split the calculation into before midnight and after midnight.
Practice Problems
- Convert 7:50 PM to 24-hour format.
- A film starts at 3:15 PM and ends at 5:40 PM. How long is the film?
- Convert 245 minutes into hours and minutes.
- Aditi leaves home at 07:45 and reaches school at 08:30. How long is her journey?
- A bus departs at 10:20 AM. The journey takes 3 hours 50 minutes. When does it arrive?
- How many seconds are there in 2 hours?
- Dev starts homework at 6:15 PM and finishes at 8:05 PM. How long did he study?
- How many days are there in the months of April, May, and June combined?
Frequently Asked Questions
Q1. What is elapsed time?
Elapsed time is the amount of time that passes between a start time and an end time. It is calculated by subtracting the start time from the end time.
Q2. How do you convert from 12-hour to 24-hour format?
For AM times (except 12 AM), the hour stays the same. For PM times, add 12 to the hour. 12:00 PM stays as 12:00, and 12:00 AM becomes 00:00.
Q3. How many minutes are in a day?
A day has 24 hours. Since 1 hour = 60 minutes, a full day = 24 × 60 = 1,440 minutes.
Q4. What is a leap year?
A leap year has 366 days instead of 365. February gets 29 days instead of 28. A year is a leap year if it is divisible by 4, except century years must be divisible by 400.
Q5. How do you add time that crosses over 60 minutes?
When the minutes add up to 60 or more, carry over. For example, 45 minutes + 30 minutes = 75 minutes = 1 hour 15 minutes. Add the extra hour to the hours column.
Q6. Why is the 24-hour clock useful?
The 24-hour clock avoids confusion between AM and PM. It is used in train timetables, bus schedules, and airports. For example, 15:00 is clearly 3:00 PM.
Q7. How do you find the start time if end time and duration are given?
Subtract the duration from the end time. For example, if a journey ends at 4:30 PM and took 2 hours 15 minutes, it started at 2:15 PM.
Q8. How many weeks are in a year?
A year has 52 weeks and 1 day (or 2 extra days in a leap year).
