If two resistors have resistances $R_1 = (350 \pm 3) \text{ } \Omega$ and $R_2 = (140 \pm 4) \text{ } \Omega$, then the percentage error for the sum and difference of $R_1$ and $R_2$ are respectively:

Explain least count and least count error. Write a note on least count error.

The resistance of a wire is determined by measuring the current flowing through it and the voltage difference across its ends. If the percentage error in the measurement of current and voltage difference is $3\%$ each,what will be the percentage error in the resistance of the wire?

The percentage errors in quantities $P, Q, R$ and $S$ are $0.5\%, 1\%, 3\%$ and $1.5\%$ respectively in the measurement of a physical quantity $A = \frac{P^3 Q^2}{\sqrt{R} S}$. The maximum percentage error in the value of $A$ will be ........... $\%$.

Two resistors of resistances $R_{1} = 100 \pm 3 \ \Omega$ and $R_{2} = 200 \pm 4 \ \Omega$ are connected $(a)$ in series,$(b)$ in parallel. Find the equivalent resistance of the $(a)$ series combination,$(b)$ parallel combination. Use for $(a)$ the relation $R = R_{1} + R_{2}$ and for $(b)$ $\frac{1}{R^{\prime}} = \frac{1}{R_{1}} + \frac{1}{R_{2}}$ and $\frac{\Delta R^{\prime}}{R^{\prime 2}} = \frac{\Delta R_{1}}{R_{1}^{2}} + \frac{\Delta R_{2}}{R_{2}^{2}}$.

For $z = a^{2} x^{3} y^{1/2}$,where $a$ is a constant. If the percentage error in the measurement of $x$ and $y$ are $4\%$ and $12\%$,respectively,then the percentage error for $z$ will be $........... \%$.