2020 Phase-2 Units and MeasurementsMean absolute error and relative error Medium Question 29 of 53 in Units and Measurements

Time intervals measured by a clock give the following readings: 1.25 s, 1.24 s, 1.27 s, 1.21 s and 1.28 s. What is the percentage relative error of the observations?

A 1.6%
B 2%
C 4%
D 16%

The answer is A.

Solution

Mean $=\dfrac{1.25+1.24+1.27+1.21+1.28}{5}=1.25$ s. Absolute deviations: $0,0.01,0.02,0.04,0.03$; mean absolute error $=\dfrac{0+0.01+0.02+0.04+0.03}{5}=0.02$ s. Percentage relative error $=\dfrac{0.02}{1.25}\times100\approx1.6\%$.

Concept Mean absolute error and relative error

Units and Measurements in past papers

53 questions from this chapter have appeared across 25 exam years.