Converting Time

Converting Between Different Units of Time

Time does not follow a decimal system (based on 10s and 100s). Instead, it follows specific conversions:

Common Time Conversions:

• 1 minute = 60 seconds
• 1 hour = 60 minutes
• 1 day = 24 hours
• 1 week = 7 days
• 1 year = 12 months
• 1 year = 365 days (or 366 in a leap year)

Example:

Convert 2.5 hours into minutes.

$$2.5 \times 60 = 150 \text{minutes}$$

Final Answer: 150 minutes.

 
12-Hour vs 24-Hour Clocks

• 12-hour clock: Uses AM (midnight to noon) and PM (noon to midnight).
• 24-hour clock: Uses hours 00:00 to 23:59, with midnight as 00:00 and 11:59 PM as 23:59.

Example: Convert 3:45 PM to 24-hour time.

$$3 : 45 + 12 = 15 : 45$$

 
Final Answer: 15:45 (24-hour format).

Example: Convert 07:30 to 12-hour format.

• Since 07:30 is less than 12, it remains AM. Final Answer: 7:30 AM.

 

Reading Time from Clocks

Analogue Clocks:

• Hour hand: Short hand (moves every 12 hours).
• Minute hand: Long hand (moves every 60 minutes).

Example: The hour hand is between 4 and 5, and the minute hand is at 30.

Final Answer: 4:30 (or 16:30 in 24-hour format).

Digital Clocks:

Can use either 12-hour or 24-hour format.

A colon (:) is often used between hours and minutes.

AM/PM is not needed in a 24-hour format.

Calculating Time Differences

To find time differences:

1. Break the time into chunks: Add minutes first, then whole hours.
2. Adjust for AM/PM changes if using the 12-hour clock.

Example: A train leaves at 11:23 AM and arrives at 2:27 PM. Find the journey time.

 

Step 1: Minutes to the next hour

$$11 : 23 + 37 \text{minutes} = 12 : 00PM$$

Step 2: Add whole hours

$$12 : 00 + 2 \text{hours} = 2 : 00PM$$

Step 3: Add remaining minutes

$$2 : 00 + 27 \text{minutes} = 2 : 27PM$$

Final Answer: 3 hours 4 minutes.

 

Using Bus and Train Timetables

Transport timetables often use the 24-hour clock. Each column represents a different bus or train.

Example: A bus departs 08:00 from Stop A and arrives at Stop B at 08:40.

Time taken:

$$08 : 40 - 08 : 00 = 40 \text{minutes}$$

Final Answer: 40 minutes.

 

Converting Time Zones

Different countries have different time zones based on their position on Earth.

Example: If it is 11:36 AM in London, and New York is 5 hours behind, then:

$$11 : 36 - 5 \text{hours} = 06 : 36AM$$

Final Answer: 6:36 AM in New York.

 

Example: A flight from Madrid to Chicago departs at 07:30 AM Madrid time and takes 9 hours 45 minutes. Madrid is 7 hours ahead of Chicago. Find the local arrival time in Chicago.

Step 1: Find arrival time in Madrid time

$$07 : 30 + 9 \text{hours} 45 \text{minute} = 17 : 15$$

Step 2: Convert to Chicago time

$$17 : 15 - 7 \text{hours} = 10 : 15AM$$

Final Answer: 10:15 AM Chicago time.