Lesson 4: Solve Time Problems

Property

The fundamental relationships for converting time are:
$1 \text{ hour} = 60 \text{ minutes}$
$1 \text{ minute} = 60 \text{ seconds}$
$1 \text{ hour} = 3600 \text{ seconds}$

Examples

• Convert 450 seconds to minutes: $450 \div 60 = 7.5$ minutes, or 7 minutes and 30 seconds.
• Convert 2 hours and 5 minutes into seconds: $(2 \times 3600) + (5 \times 60) = 7200 + 300 = 7500$ seconds.
• Convert 4000 seconds to hours, minutes, and seconds: $4000 \div 3600 = 1$ with a remainder of $400$. So, 1 hour and 400 seconds. Then, $400 \div 60 = 6$ with a remainder of $40$. The final answer is 1 hour, 6 minutes, and 40 seconds.

Explanation

To convert between hours, minutes, and seconds, use the standard conversion factors. When converting from a larger unit to a smaller unit (e.g., hours to seconds), you multiply. When converting from a smaller unit to a larger unit (e.g., seconds to minutes), you divide. For mixed units, convert each part to the desired unit and then add them together.

Property

To convert mixed units (e.g., hours and minutes) to a single smaller unit (minutes):

To convert a single smaller unit (e.g., seconds) to mixed units (minutes and seconds), use division with a remainder:

Examples

Property

To find a fraction of a time interval, multiply the time by the fraction. It is often easiest to first convert the time to a single, smaller unit (e.g., minutes or seconds) before multiplying.

Examples