Two coherent monochromatic light beams of intensities 4 I and 9 I are superimposed. The difference between the maximum and minimum intensities in the…

Two coherent monochromatic light beams of intensities $\displaystyle 4$ I and $\displaystyle 9$ I are superimposed. The difference between the maximum and minimum intensities in the resulting interference pattern is $\displaystyle x \mathrm{I}$. The value of $\displaystyle x$ is $\displaystyle \_\_\_\_$.