AlgebraEasy–MediumHours until a battery is empty
Algebra practice question
The charge C, in percent, of a laptop battery after t hours of use is given by C = 100 − 20t. After how many hours of use is the charge 0?
Answer: 5
100 − 20t = 0 gives t = 5.
Common wrong answers
- If you answered 20
- 20 is the percent lost per hour.
- If you answered 80
- 80 is the charge after 1 hour.
- If you answered 2000
- 2000 multiplies 100 by 20.
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