Please answer this question in detail and with an explanation. Thank you for your help.

A store has only 4 types of items: jackets, shoes, shirts, and pants, each in their own store section. You go on a shopping trip with 5 friends. At each store section, you find 1 item you like with probability 1/3 (and you leave the store section disliking everything with probability 2/3). If you find an item you like, then the store has that item in your size with probability p. (This value p is common across all store sections). If you like an item, and you can find your size, then you buy it. The same decision making process that you go through holds for all of your friends. In addition, you and all of your friends make choices independently of one another. How many items should you and your friends expect to buy altogether as a group