In a Diffraction Grating Experiment, Light of 600 Nm Wavelength

Short Answer

In a diffraction grating experiment, light of 600 nm wavelength produces a first-order
maximum 0.35 mm from the central maximum on a distant screen. On the same screen, a
second monochromatic source produces a third-order maximum 0.87 mm from the
central maximum when it passes through the same diffraction grating. What is the
wavelength of the light from the second source?