Originally Posted by

**sweeetcaroline** Okay I have a question on a probability problem that I'm trying to figure out. Here it is: Shuffle an ordinary deck of playing cards containing four aces. Then turn up cards from the top until the first ace appears. On the average, how many cards are required to produce the first ace?

How exactly should I go about starting this or trying to find the average? I mean I guess that each probability changes after each card is picked up but I'm not really sure. Please help!