ACT Preparation / Unit 19 ACT 1815 worked example, 60 to 90 seconds
Interpolating a Value
The idea
A value between measured points is estimated in three steps. First, find the two measured points on either side of the condition the question names. Second, find where the condition sits between them: halfway, a quarter of the way, and so on. Third, move the same fraction of the way between the two measured values, and check that the estimate lies between them.
In practice
Worked example: an invented table gives a sensor's reading as 331 units at 0 degrees and 343 units at 20 degrees. Estimate it at 5 degrees. Five is a quarter of the way from 0 to 20. The difference is 343 − 331 = 12, and a quarter of it is 3, so the estimate is 331 + 3 = 334 units.
Where people slip
An interpolated value must lie between its neighbors. An estimate below 331 or above 343 signals an arithmetic slip.
Your place on the trail
Every lesson rests on earlier ones and opens later ones. Tap any to jump.
Builds on
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