AlgebraEasy–MediumWhen a linear model reaches zero
Algebra practice question
A candle is 200 millimetres tall and burns down at a constant 8 millimetres per hour. After how many hours will the candle be completely burned?
Answer: 25
200 − 8t = 0 gives t = 25.
Common wrong answers
- If you answered 16
- 16 comes from 200 ÷ 12.5 or a similar slip; 200 ÷ 8 = 25.
- If you answered 192
- 192 is the height after ONE hour.
- If you answered 1600
- 1,600 multiplies 200 by 8 instead of dividing.
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