In number `1` is drawn in first slip, then, possible outcomes will be,
`(1,2),(1,3),(1,4)`
In number `2` is drawn in first slip, then, possible outcomes will be,
`(2,1),(2,3),(2,4)`
In number `3` is drawn in first slip, then, possible outcomes will be,
`(3,1),(3,2),(3,4)`
In number `4` is drawn in first slip, then, possible outcomes will be,
`(4,1),(4,2),(4,3)`
So, sample space will be,
`(1,2),(1,3),(1,4),` `(2,1),(2,3),(2,4),` `(3,1),(3,2),(3,4)`, `(4,1),(4,2),(4,3)`