AlgebraVery hardPrediction from two readings of a linear meter
Algebra practice question
A water meter's reading is a linear function of the number of days since it was installed. On day 1 it read 5 units and on day 3 it read 11 units. What will it read on day 10?
Answer: 32
The rate is 3 units per day and the day-0 reading is 2, so day 10 reads 3(10) + 2 = 32.
Common wrong answers
- If you answered 30
- 30 forgets the day-0 reading.
- If you answered 35
- 35 uses a day-0 reading of 5.
- If you answered 38
- 38 counts 11 steps of 3 from 5.
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