$A$ simple pendulum is being used to determine the value of gravitational acceleration $g$ at a certain place. The length of the pendulum is $25.0 \; cm$ and a stopwatch with $1 \; s$ resolution measures the time taken for $40$ oscillations to be $50 \; s$. The accuracy in $g$ is ....... $\%$ (in $.40$)

Following observations were taken with a vernier callipers while measuring the length of a cylinder:
$3.29 \, cm, 3.28 \, cm, 3.29 \, cm, 3.31 \, cm, 3.28 \, cm, 3.27 \, cm, 3.29 \, cm, 3.30 \, cm$
Find the absolute error in the fourth and eighth observations.

$A$ cuboid has volume $V = l \times l \times \sqrt{l} = l^{2.5}$, where $l$ is the length of one side. When the length $l$ is measured by a meter scale of least count $1 \text{ mm}$, the relative percentage error in the measurement of its volume is $6.25\%$. Then the relative percentage error in measurement of its length and the value of the length $l$ is:

The length of a pendulum is measured as $1.01 \ m$ and the time for $30$ oscillations is measured as $1 \ minute \ 3 \ s$. The error in length is $0.01 \ m$ and the error in time is $3 \ s$. The percentage error in the measurement of acceleration due to gravity is: (in $\%$)

Write a note on the combination of errors.