Consider two physical quantities $$A$$ and $$B$$ related to each other as $$E=\frac{B-x^2}{A t}$$ where $$E, x$$ and $$t$$ have dimensions of energy, length and time respectively. The dimension of $$A B$$ is

The measured value of the length of a simple pendulum is $$20 \mathrm{~cm}$$ with $$2 \mathrm{~mm}$$ accuracy. The time for 50 oscillations was measured to be 40 seconds with 1 second resolution. From these measurements, the accuracy in the measurement of acceleration due to gravity is $$\mathrm{N} \%$$. The value of $$\mathrm{N}$$ is:

If the percentage errors in measuring the length and the diameter of a wire are $$0.1 \%$$ each. The percentage error in measuring its resistance will be:

A force is represented by $$F=a x^2+b t^{\frac{1}{2}}$$

where $$x=$$ distance and $$t=$$ time. The dimensions of $$b^2 / a$$ are: