Given uniformly randomly chosen x on the interval (1,5) and y on the interval (1,5) find the probability of each:

[x] + [y] = [x+y]

[x] - [y] = [x-y]

[x] * [y] = [x*y]

[x] / [y] = [x/y]

Where [x] is the floor function, the greatest integer less than or equal to x.