The middle-point is also the number that is halfway into the set. To find the middle-point, the data should be arranged in order from least to greatest. If there is an even number of items in the data set, then the middle-point is found by taking the mean (average) of the two middlemost numbers.
The law of optics applicable in this scenario is the Snell's Law which states that the ratio of the index of refraction of two media is equal to the ratio of the sine of the angle of reflection and sine of the angle of refraction. In equation form: n₁ / n₂ = sin b / sin a
