Given number of slips in the box are 4
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1234
Now, if the person withdraws first slip with number 1 on it, then in second draw 2,3 or 4 is possible.
Similarly, if the person withdraws first slip with number 2 on it, then in second draw 1,3 or 4 is possible.
Similarly, if the person withdraws first slip with number 3 on it, then in second draw 1,2 or 4 is possible.
Similarly, if the person withdraws first slip with number 4 on it, then in second draw 1,2 or 3 is possible.
So, the sample space for the given experiment is
S={(1,2),(1,3),(1,4),(2,1),(2,3),(2,4),(3,1),(3,2),(3,4),(4,1),(4,2),(4,3)}