The best method to reduce random error is

Two intervals of time are measured as $\Delta t_1 = (2.00 \pm 0.02) \ s$ and $\Delta t_2 = (4.00 \pm 0.02) \ s$. The value of $\sqrt{(\Delta t_1)(\Delta t_2)}$ with correct significant figures and error is

An experiment measures quantities $a, b$ and $c$,and quantity $X$ is calculated from $X = ab^2 / c^3$. If the percentage errors in $a, b$ and $c$ are $\pm 1\%, \pm 3\%$ and $\pm 2\%$,respectively,then the percentage error in $X$ will be

In an experiment to measure the height of a bridge by dropping a stone into water underneath,if the error in the measurement of time is $0.1\;s$ at the end of $2\;s$,then the error in the estimation of the height of the bridge will be (in $;m$)

$A$ current of $(2.5 \pm 0.05) \ A$ flows through a wire and develops a potential difference of $(10 \pm 0.1) \ V$. The resistance of the wire in $\Omega$ is:

The errors in the measurement which arise due to unpredictable fluctuations in temperature and voltage supply are: