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Measurement and Experimentation — PHYSICS STD 9 — Question

ICSE BoardEnglish MediumSTD 9PHYSICSMeasurement and Experimentation4 Marks
Question
(a) State the formula for calculating percentage error
(b) Is it possible to increase the degree of accuracy by mathematical manipulations? Support your answer by an example.
✓

Answer

(a) The percentage error can be calculated by the formula :
$
\text { Percentage error }=\frac{\text { Absolute error }}{\text { Actual value }} \times 100
$
(b) It is not possible to increase the degree of accuracy by mathematical manipulations. For examples: When a number of values are added or subtracted, the result cannot be more accurate than the least accurate value.
Image
In the above addition 72.5 has least accuracy. When we . say 72.5, it implies that value lies between 72.45 and 72.55 and 72.5 is the most probable value. Thus the error in 72.5 is +0.05. As the final result cannot be more accurate than least accurate observation, so the correct and most reliable answer in the above addition is 72.9.

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