AlgebraHardTime for a battery to drain to a level
Algebra practice question
A phone's battery drains at a constant rate, from 100 percent at 8 am to 40 percent at noon. How many hours after noon will the battery reach 10 percent?
Answer: 2
It loses 60 percent in 4 hours, or 15 percent per hour. From 40 to 10 percent is 30 percent, which takes 2 hours.
Common wrong answers
- If you answered 3
- 3 uses 10 percent per hour.
- If you answered 4
- 4 repeats the morning's duration.
- If you answered 6
- 6 counts from 8 am instead of from noon.
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