Fraunhofer diffraction pattern of a single slit is obtained in the focal plane of the lens of focal length $1 \mathrm{m}$. The third minimum is formed at a distance of $5 \mathrm{mm}$ from the central maximum and the wavelength of light used in the experiment is $5000\mathrm{ }\mathrm{Å}$. From the given data find the width (in $\mathrm{mm}$) of the slit used in the experiment.

Hence, the correct answer is 0.3.