Which of the following comes under the category of random errors?

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?

Measurement of two quantities along with the error is: $A = 2.5 \ ms^{-1} \pm 0.5 \ ms^{-1}$,$B = 0.10 \ s \pm 0.01 \ s$. The value of $AB$ 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 least count of a stopwatch is $0.2\, s$. The time for $20\, oscillations$ of a pendulum is measured to be $25\, s$. The percentage error in the measurement of time will be ........ $\%$

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?