I'm pretty sure that that
P(Ei) = ? / k^n
The sample space is k*k*k*k n-times.
But i don't see how to count not getting the jth player.
Assume hat every time you buy a box of Corn Flakes, you receive one of the pictures of the k players of the Florida Marlins. Over a period of time you buy n >= k boxes of Corn Flakes. Let Ej, j=1,2,3,...,k, denote the event you do not get the jth player's picture.
What is the probability of Ej?
What is the probability of Ej intersect Ei (i is just another player)?
I think once i have those I can use the inclusion-exclusion principle to answer what is the even you do not get at least one picture.
I think that you both need to rethink this problem.
Suppose you toss a die ten times. What is the probability of not getting a two?
In the problem if k=6 then what is the probability of not getting player b in ten boxes?
Toss a die ten times; what is the probability of getting neither a two nor a three?
If k=6 then in buying 10 boxes what is the probability of getting neither player b nor player c?
Toss a die ten times; what is the probability of getting none of 2, 3 or 4?
If k=6 then in buying 10 boxes what is the probability of getting none of player b, player c or player d?