An elevator containing p passengers is at the ground floor of a building with n floors. On its way to the top of the building, the elevator will stop if a passenger needs to get off. Passengers get off at a particular floor with probability 1/n. Find the expected number of stops the elevator makes. (Use indicators, letting I_k= 1if the kth floor is a stop. Be careful: more than one passenger can get off at a floor.)

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