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Working out a rate of change from two readings, a trainee uses the later reading first and the earlier one second, keeping each pair of values together. What happens to the answer?
AIt doubles, because the gap is counted twice
BIt comes out with the sign the wrong way round
CIt is the same, because both pairs stay matched
DIt cannot be worked out in that order at all
Answer & Solution
Correct answer: C. It is the same, because both pairs stay matched
1. A rate of change is the change in output divided by the change in input.
2. Swapping which reading comes first flips the sign on the top and on the bottom of that division.
3. Two sign flips cancel, so the answer is unchanged.
4. Option B would be right only if the values from one reading were split across the two pairs, which is not what happened here.
5. So the answer is the same, option C.
_Source: OpenStax College Algebra (CC BY 4.0), Ch 4 "Linear Functions", section 4.1 Linear Functions_
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