Thank you for using the timer - this advanced tool can estimate your performance and suggest more practice questions. We have subscribed you to Daily Prep Questions via email.

Customized for You

we will pick new questions that match your level based on your Timer History

Track Your Progress

every week, we’ll send you an estimated GMAT score based on your performance

Practice Pays

we will pick new questions that match your level based on your Timer History

Not interested in getting valuable practice questions and articles delivered to your email? No problem, unsubscribe here.

It appears that you are browsing the GMAT Club forum unregistered!

Signing up is free, quick, and confidential.
Join other 500,000 members and get the full benefits of GMAT Club

Registration gives you:

Tests

Take 11 tests and quizzes from GMAT Club and leading GMAT prep companies such as Manhattan GMAT,
Knewton, and others. All are free for GMAT Club members.

Applicant Stats

View detailed applicant stats such as GPA, GMAT score, work experience, location, application
status, and more

Books/Downloads

Download thousands of study notes,
question collections, GMAT Club’s
Grammar and Math books.
All are free!

Thank you for using the timer!
We noticed you are actually not timing your practice. Click the START button first next time you use the timer.
There are many benefits to timing your practice, including:

Each person out of 6 has 6 options, hence total # of outcomes is 6^6;

Favorable outcomes will be 6!, which is # of ways to assign 6 different buttons to 6 people: 1-2-3-4-5-6 (floors) A-B-C-D-E-F (persons) B-A-C-D-E-F (persons) B-C-A-D-E-F (persons) ... So basically # of arrangements of 6 distinct objects: 6!.

Re: Six Six people are on an elevator that stops at exactly 6 [#permalink]

Show Tags

19 Feb 2012, 06:55

Hi, could you please tell me the mistake in the following logic?

First person entering pushes one button, it doesn't matter which: p=1 Second person pushes a button that has not been pressed before. Since one is already pushed, only 5 remain: p=5/6 Same logic for third person: p=4/6 . . .

This leaves us with The probability of all pushing a different button of: 1*5/6*4/6*4/6*2/6*1/6 or 5!/6^5

Hi, could you please tell me the mistake in the following logic?

First person entering pushes one button, it doesn't matter which: p=1 Second person pushes a button that has not been pressed before. Since one is already pushed, only 5 remain: p=5/6 Same logic for third person: p=4/6 . . .

This leaves us with The probability of all pushing a different button of: 1*5/6*4/6*4/6*2/6*1/6 or 5!/6^5

Where's the mistake?

There is no mistake: 6!/6^6=(5!*6)/(6^5*6)=5!/6^5, the same answers. _________________

Re: Six Six people are on an elevator that stops at exactly 6 [#permalink]

Show Tags

07 Jun 2013, 07:52

4

This post received KUDOS

1

This post was BOOKMARKED

Gwydion wrote:

Hi, could you please tell me the mistake in the following logic?

First person entering pushes one button, it doesn't matter which: p=1 Second person pushes a button that has not been pressed before. Since one is already pushed, only 5 remain: p=5/6 Same logic for third person: p=4/6 . . .

This leaves us with The probability of all pushing a different button of: 1*5/6*4/6*4/6*2/6*1/6 or 5!/6^5

Where's the mistake?

Expanding on Gwydion's post - it is true that p=1, but because the answers all have 6 in them, the first person should be written as p=6/6 to make it easier to see the answer:

First person walks in and can push any button (6/6) Probability that second person will press any of the remaining 5 buttons (5/6) Probability that third person will press any of the remaining 4 buttons (4/6) Probability that fourth person will press any of the remaining 3 buttons (3/6) Probability that fifth person will press either of the remaining 2 buttons (2/6) Probability that sixth person will press the remaining button (1/6)

Re: Six people are on an elevator that stops at exactly 6 floors [#permalink]

Show Tags

10 Jul 2014, 02:31

Hello from the GMAT Club BumpBot!

Thanks to another GMAT Club member, I have just discovered this valuable topic, yet it had no discussion for over a year. I am now bumping it up - doing my job. I think you may find it valuable (esp those replies with Kudos).

Want to see all other topics I dig out? Follow me (click follow button on profile). You will receive a summary of all topics I bump in your profile area as well as via email. _________________

Re: Six people are on an elevator that stops at exactly 6 floors [#permalink]

Show Tags

21 May 2015, 06:15

Does this logic work ?

Assuming we are calculating the options for that one person we use the number of floors are the options. Person A presses at the ground floor has 6 options, then 5 options as so on as he goes up. so 6*5*4*3*2*1 = 6!

Assuming we are calculating the options for that one person we use the number of floors are the options. Person A presses at the ground floor has 6 options, then 5 options as so on as he goes up. so 6*5*4*3*2*1 = 6!

Re: Six people are on an elevator that stops at exactly 6 floors [#permalink]

Show Tags

21 May 2015, 07:10

1

This post received KUDOS

EgmatQuantExpert wrote:

shallow9323 wrote:

Does this logic work ?

Assuming we are calculating the options for that one person we use the number of floors are the options. Person A presses at the ground floor has 6 options, then 5 options as so on as he goes up. so 6*5*4*3*2*1 = 6!

Assuming we are calculating the options for that one person we use the number of floors are the options. Person A presses at the ground floor has 6 options, then 5 options as so on as he goes up. so 6*5*4*3*2*1 = 6!

This is the kickoff for my 2016-2017 application season. After a summer of introspect and debate I have decided to relaunch my b-school application journey. Why would anyone want...

Check out this awesome article about Anderson on Poets Quants, http://poetsandquants.com/2015/01/02/uclas-anderson-school-morphs-into-a-friendly-tech-hub/ . Anderson is a great place! Sorry for the lack of updates recently. I...

Time is a weird concept. It can stretch for seemingly forever (like when you are watching the “Time to destination” clock mid-flight) and it can compress and...