Accuracy of measurement is determined by

The percentage error in the measurement of $g$ is $.....\%$ (Given that $g = \frac{4 \pi^2 L}{T^2}$,$L = (10 \pm 0.1) \, cm$,$T = (100 \pm 1) \, s$)

Error in the measurement of radius of a sphere is $0.2\%$. The error in the calculated value of its volume is ......... $\%$

The radius of a sphere is $(5.3 \pm 0.1) \, cm$. The percentage error in its volume is

$A$ student uses a simple pendulum of exactly $1 \ m$ length to determine $g$,the acceleration due to gravity. He uses a stopwatch with a least count of $1 \ s$ for this and records $40 \ s$ for $20$ oscillations. For this observation,which of the following statement$(s)$ is (are) true?
$(A)$ Error $\Delta T$ in measuring $T$,the time period,is $0.05 \ s$
$(B)$ Error $\Delta T$ in measuring $T$,the time period,is $1 \ s$
$(C)$ Percentage error in the determination of $g$ is $5 \%$
$(D)$ Percentage error in the determination of $g$ is $2.5 \%$

$A$ metal wire has mass $(0.4 \pm 0.002) \, g$,radius $(0.3 \pm 0.001) \, mm$ and length $(5 \pm 0.02) \, cm$. The maximum possible percentage error in the measurement of density will nearly be $.......\%$