At the hotel Excelsior, Melvyn had stopped by the security office run by his friend Zack. They were watching the elevator on the split screen monitor, with one screen for each of the ten floors of the hotel and the ground floor.
“Zack, you see the seven people entering the elevator on the ground floor?”
“Sure, Melvyn, especially that hot blonde that just wiggled in before the door closed,” said Zack, chewing on his bubble gum.
“Zack, I’ll bet you a hundred bucks that there will not be a group of exactly three people getting off the elevator at any floor,” said Melvyn.
“You’re on, I could really use a hundred bucks,” chuckled Zack.
“Are you really sure that three persons will be getting off at some floor?” quieried Melvyn, raising an eyebrow.
“That’s what I’m betting on, Melvyn.”
“Well, let’s see how it goes, Zack.” Melvyn made himself comfortable in an armchair to watch the monitor.
What do you figure are the chances that Melvyn will win his bet with Zack?
Can you work out the probability that only one person gets off the elevator at each stop?