I just learned about Random Variables and Expected values and i tried solving the following question from my textbook
In an urn are N white balls. The balls are arbitrarily taken and at the same time a similar red ball is placed in the urn. So the number of balls in the urn has not changed. The same process is repeated until all N balls in the urn are red. Let X be the number of withdrawals made. Calculate the expected value of X
I'm having real struggles to Modell this problem correctly, i tried via diffrent distribution concepts but non of them worked. Could someone give me some details on how to structure this problem