A ray of light is incident on an interface separating two media at an angle of incidence equal to 45°, for which the angle of refraction is 30°. The refractive index of the second medium with respect to the first is equal to:
\(\frac{\sqrt{3}}{2}\)
\(\frac{1}{\sqrt{2}}\)
\(\frac{1}{2}\)
\(\sqrt{2}\)
If the mean of the following data is 4 , find the missing frequency.
| x | 3 | 5 | 9 | 2 |
| f | 3 | 4 | - | 8 |