Page 1 - Microsoft Word - HA 1

Lesson Notes: Time and Conversion into Decimals

1. Understanding Time as a Fraction and Decimal

Time is measured in hours, minutes, and seconds, and can be expressed as a
fraction or a decimal of an hour.

• 1 hour = 60 minutes

• 1 minute = 60 seconds

• ½ hour = 30 minutes = 0.5 hours

• ¼ hour = 15 minutes = 0.25 hours

• ¾ hour = 45 minutes = 0.75 hours

2. Converting Minutes into Decimal Form

To convert minutes into decimal hours:

• Divide the number of minutes by 60 (since 1 hour = 60 minutes).

Minutes Fraction of an Hour Decimal Equivalent

15 minutes 15/60 = ¼ 0.25

30 minutes 30/60 = ½ 0.5

45 minutes 45/60 = ¾ 0.75

10 minutes 10/60 0.166...

20 minutes 20/60 0.333...

3. Converting Seconds into Decimal Form

To express seconds as decimal minutes:

• Divide seconds by 60 (since 1 minute = 60 seconds).

To express seconds as decimal hours:

• First convert to minutes, then divide by 60 again.

Example:

• 30 seconds = 30 ÷ 60 = 0.5 minutes

• 90 seconds = 90 ÷ 60 = 1.5 minutes

• 90 seconds in hours = 1.5 ÷ 60 = 0.025 hour