The least count of a stopwatch is $\frac{1}{5} \ s$. The time for $20$ oscillations of a pendulum is measured to be $25 \ s$. The percentage error in the measurement of time will be .......... $\%$

Two clocks are being tested against a standard clock located in a national laboratory. At $12:00:00$ noon by the standard clock,the readings of the two clocks are

Day	Clock $1$	Clock $2$
Monday	$12:00:05$	$10:15:06$
Tuesday	$12:01:15$	$10:14:59$
Wednesday	$11:59:08$	$10:15:18$
Thursday	$12:01:50$	$10:15:07$
Friday	$11:59:15$	$10:14:53$
Saturday	$12:01:30$	$10:15:24$
Sunday	$12:01:19$	$10:15:11$

If you are doing an experiment that requires precision time interval measurements,which of the two clocks will you prefer?

The percentage errors in measurements of mass and speed of a body are $2 \%$ and $3 \%$ respectively. What is the percentage error in kinetic energy of the body (in $\%$)?

$A$ quantity $Q$ is formulated as $Q = X^{-2} Y^{\frac{3}{2}} Z^{-\frac{2}{5}}$. $X, Y$ and $Z$ are independent parameters which have fractional errors of $0.1, 0.2$ and $0.5$,respectively,in measurement. The maximum fractional error of $Q$ is:

The period of oscillation of a simple pendulum is given by $T = 2\pi \sqrt{\frac{l}{g}}$,where $l$ is about $100 \, cm$ and is known to have $1 \, mm$ accuracy. The period is about $2 \, s$. The time of $100$ oscillations is measured by a stopwatch of least count $0.1 \, s$. The percentage error in $g$ is ......... $\%$

The outer and inner radii of a hollow cylinder are $(4.23 \pm 0.01) \text{ cm}$ and $(3.89 \pm 0.01) \text{ cm}$ respectively. What is the thickness of the wall of the cylinder?