In an experiment to find acceleration due to gravity (g) using simple pendulum, time period of $0.5 \mathrm{~s}$ is measured from time of 100 oscillation with a watch of $1 \mathrm{~s}$ resolution. If measured value of length is $10 \mathrm{~cm}$ known to $1 \mathrm{~mm}$ accuracy, The accuracy in the determination of $\mathrm{g}$ is found to be $x \%$. The value of $x$ is $\underline{\hspace{2cm}}$.