Stereotypical Barbie is hosting a house party to which 6 other uniquely named Barbies are invited (e.g., Doctor Barbie, Weird Barbie, etc.). Every time the doorbell rings, it's equally likely to be either an invited Barbie or a Ken. The party starts when at least 4 of the invited Barbies arrive, and no more Kens are admitted after the 6th invited Barbie arrives. The house has unlimited capacity, and the doorbell can ring at any time. Don't count the host of the party, Stereotypical Barbie, in any of the problems/counts below.
We record the number of Kens that arrive between the first and second Barbie arrivals. The number of Kens that could arrive between the first and second Barbie could theoretically be infinite.
s = [0, ?]