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A ray of light that travels obliquely from one transparent medium into another will change its direction in the second medium. The extent of the change in direction that takes place in a given pair of media may be expressed in terms of the refractive index. The refractive index is also related to?the relative speed of propagation of light in different media.
If the refractive index of four different media X1, X2, X3, and X4?is given in the table below, answer the questions using and analysing the table given below:

MediumX1X2X3X4Refractive index1.361.521.642.42If a ray of light travels from medium X?1?to X?2, the refractive index of medium X?2?relative to X?1?will be