Similar to this question: Probability Question - An elevator & 5 Passengers

Five people enter an elevator in the basement of a seven story building (ie. the building has a basement, plus floors 1-7). Each person independently selects one of the seven floors at random. No new people get on the elevator.

How likely it is that 3 passengers get off on one floor, and the remaining 2 get off on a different floor but also together?

I thought I could do:

(C(5,3) * 7 * C(2,2) * 6)/7^5

= 0.025 or %2.5

Is this correct?

  • $\begingroup$ I see now what you meant sorry I had a typo. It has been fixed. $\endgroup$ – user197976 Dec 6 '14 at 2:59
  • $\begingroup$ Your answer looks good to me. $\endgroup$ – peterwhy Dec 6 '14 at 3:03

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