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    Four identical rods have a square cross-section. The rods are placed side by side and their total
    width is measured with vernier calipers, as shown.
    vernier calipers
    four square
    cross-section rods
    The measurement is (8.4 ± 0.1)mm and the zero reading on the calipers is (0.0 ± 0.1)mm.
    What is the width of one rod?
    A (2.10 ± 0.025)mm
    B (2.10 ± 0.05)mm
    C (2.1 ± 0.1)mm
    D (2.1 ± 0.2)mm

    Answer is B

    The are two errors that must be added - the zero and measurement.
    Divide width and error by four.

    Not sure that 3 significant figures should be quoted with confidence.
    Need to think about that

    The previous answer is correct ..what is more the zero error should be 0.025.add also error of the measurements 0.1 ÷ 4 = 0.025 ..now the total error will be 0.05 which is found only in answer B.about zero error 0.1÷8.4)×100=1.19....1.19×2.1/100 =0.025
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