Math Problem Statement
Mia cleans her teeth for 3 minutes. When she finishes cleaning her teeth, the clock shows 08:02:20. Write the time the clock showed when she started cleaning her teeth.
Solution
To solve this:
The clock shows 08:02:20 when Mia finishes cleaning her teeth. She cleaned her teeth for 3 minutes.
To find the time when she started cleaning her teeth, subtract 3 minutes from 08:02:20:
-
Subtract 3 minutes from the minutes portion (02):
.
Since this result is negative, borrow 1 hour (60 minutes):
. -
Adjust the hour accordingly: .
Thus, the time when Mia started cleaning her teeth was 07:59:20.
Let me know if you'd like more details!
Here are some related questions to consider:
- How can you verify time calculations like this?
- What would happen if the initial time crossed into another day?
- How does this apply to real-life scheduling problems?
- How would you adjust if seconds were also involved in subtraction?
- What if she cleaned her teeth for a duration not in whole minutes?
Tip: Always work backward carefully when subtracting across hours!
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Math Problem Analysis
Mathematical Concepts
Time calculation
Subtraction with borrowing
Formulas
Time subtraction with hours, minutes, and seconds
Theorems
Basic rules of time arithmetic
Suitable Grade Level
Grade 4-6