For the weight of the box that she measured, Beatriz determined the margin of error as 23.5 pounds to 24.5 pounds. What was the greatest possible error for her actual measurement?

The measurement is centered at 24 pounds, halfway between 23.5 and 24.5. The greatest possible error is the distance from 24 to either endpoint: 24.5 − 24 = 0.5 pounds. So the greatest possible error is 0.5 pounds.

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