Delhi radio station broadcast at 819 kHz frequency. The wavelength of radio waves will be -

Using the wave relation $\lambda = \frac{c}{\nu}$, where $c = 3 \times 10^8\text{ m/s}$ and $\nu = 819\text{ kHz} = 819 \times 10^3\text{ Hz}$: $\lambda = \frac{3 \times 10^8}{8.19 \times 10^5} \approx 366.3\text{ m} = 3.66 \times 10^2\text{ m}$.