Four persons measure the length of a rod as 20.00 cm, 19.75 cm, 17.01 cm and 18.25 cm. The relative error in the measurement of average length of the rod is: (a) 0.18 (b) 0.24 (c) 0.06 (d) 0.08

Answer: (c). Mean = (20.00 + 19.75 + 17.01 + 18.25)/(4) = 18.75 cm Absolute errors: 1.25, 1.00, 1.74, 0.50; mean = 4.49/4 ≈ 1.12 cm Relative error = (1.12)/(18.75) ≈ 0.06 So the answer is (c).

Four persons measure the length of a rod as 20.00 cm, 19.75 cm, 17.01… | JEE Main 2026 (23 Jan, Shift 1)

Q1JEE Main 2026 · 23 JAN · SHIFT 1Easy

Errors in Measurement

Four persons measure the length of a rod as $20.00\text{ cm}, 19.75\text{ cm}, 17.01\text{ cm}$ and 18.25 cm. The relative error in the measurement of average length of the rod is:

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Answer: (c)

Mean $= \frac{20.00 + 19.75 + 17.01 + 18.25}{4} = 18.75\ \text{cm}$
Absolute errors: $1.25, 1.00, 1.74, 0.50$ ; mean $= \frac{4.49}{4} \approx 1.12\ \text{cm}$
Relative error $= \frac{1.12}{18.75} \approx 0.06$
So the answer is (c).

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