The most accurate reading of the length of a $6.28 \,cm$ long fibre is ............... $cm$.

$A$ physical quantity $Q$ is found to depend on quantities $a, b, c$ by the relation $Q = \frac{a^4 b^3}{c^2}$. The percentage errors in $a, b,$ and $c$ are $3 \%, 4 \%,$ and $5 \%$ respectively. Then,the percentage error in $Q$ is: (in $\%$)

Two students $P$ and $Q$ perform an experiment to verify Ohm's law for a conductor with resistance $R$. They use a current source and a voltmeter with least counts of $0.1 \, mA$ and $0.1 \, mV$,respectively. The plots of the variation of voltage drop $V$ across $R$ with current $I$ for both are shown below. Which statement is most likely to be correct?

$A$ physical quantity $A$ is dependent on four other physical quantities $p, q, r,$ and $s$ as given by the relation $A = \frac{\sqrt{pq}}{r^2s^3}.$ If the percentage errors of measurement in $p, q, r,$ and $s$ are $1\%, 3\%, 0.5\%,$ and $0.33\%$ respectively,then the maximum percentage error in $A$ is .......... $\%$.

Four students measure the height of a tower. Each student uses a different method and each measures the height many different times. The data for each are plotted below. The measurement with the highest precision is

Consider a series of measurements of the length of a box in an experiment. The readings are $2.4 \ m, 2.5 \ m, 2.6 \ m, 2.8 \ m, 3.0 \ m$. What would be the relative error?