Calculate the mean percentage error in five observations: $80.0, 80.5, 81.0, 81.5, 82.0$. (in $\%$)

The resistance $R = V / I$ where $V = (100 \pm 5) \; V$ and $I = (10 \pm 0.2) \; A$. Find the percentage error in $R$. (in $\%$)

The maximum error in the measurement of the density and mass of the uniform cube are $8\%$ and $2\%$ respectively. Hence, the maximum error in the measurement of length will be (in $\%$)

In an experiment of a simple pendulum,the time period measured was $50 \, s$ for $25$ vibrations when the length of the simple pendulum was taken as $100 \, cm$. If the least count of the stopwatch is $0.1 \, s$ and that of the meter scale is $0.1 \, cm$,then the maximum possible error in the value of $g$ is .......... $\%$

$A$ projectile is thrown with velocity $U = 20 \ m/s \pm 5\%$ at an angle $60^{\circ}.$ If the projectile falls back on the ground at the same level,then which of the following values in $m$ cannot be a possible answer for the range?

The period of oscillation of a simple pendulum is $T = 2\pi(L/g)^{1/2}$. Measured value of $L$ is $10 \text{ cm}$ known to $1 \text{ mm}$ accuracy and time for $100$ oscillations is $50 \text{ s}$, using a watch of $1 \text{ s}$ resolution. The percentage error in the measurement of $g$ is (in $\%$)