What is the error in measurement done by any instrument?

If $Q = \frac{X^n}{Y^m}$ and $\Delta X$ is the absolute error in the measurement of $X,$ and $\Delta Y$ is the absolute error in the measurement of $Y,$ then the absolute error $\Delta Q$ in $Q$ is:

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

$A$ person measures the depth of a well by measuring the time interval between dropping a stone and receiving the sound of impact with the bottom of the well. The error in his measurement of time is $\delta T = 0.01 \ s$ and he measures the depth of the well to be $L = 20 \ m$. Take the acceleration due to gravity $g = 10 \ ms^{-2}$ and the velocity of sound $v = 300 \ ms^{-1}$. Then the fractional error in the measurement,$\delta L / L$,is closest to: (in $\%$)

The amount of heat produced in an electric circuit depends upon the current $(I),$ resistance $(R)$ and time $(t).$ If the error made in the measurements of the above quantities are $2\%, 1\%$ and $1\%$ respectively then the maximum possible error in the total heat produced will be ........... $\%$

If $Z = \frac{A^{2} B^{3}}{C^{4}}$,then the relative error in $Z$ will be