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:

What is the average (arithmetic mean) height of the n people [#permalink]

Show Tags

21 Mar 2010, 10:49

2

This post was BOOKMARKED

00:00

A

B

C

D

E

Difficulty:

25% (medium)

Question Stats:

68% (01:45) correct
32% (00:54) wrong based on 367 sessions

HideShow timer Statistics

What is the average (arithmetic mean) height of the n people in a certain group?

(1) The average height of the n/3 tallest people in the group is 6 feet and 2.5 inches and the average height of the rest of the people in the group is 5 feet 10 inches (2) the sum of the heights of the n people is 178 feet 9 inches

what is the average (arithmetic mean) height of the n people in a certain group?

(1) The average height of the n/3 tallest people in the group is 6 feet and 2.5 inches and the average height of the rest of the people in the group is 5 feet 10 inches

(2) the sum of the heights of the n people is 178 feet 9 inches

pranrasvij wrote:

zisis wrote:

pranrasvij wrote:

A is easily the right choice since it gives info about the rest (1-n/3) and n/3 => we dont need the final value of "n" in that case.

B gives us total height but no way to get the mean without more on "n".

so the mean height is the heights given at a ration 1:2 ????

please explain....

yep... all you have to do is the add the 2 heights and divide by 2 to get the mean height => easy to calculate (IMHO!)

Answer to the question is A, but you shouldn't divide the "sum" by 2, you should divide by \(n\).

\(Weighted \ average=\frac{sum \ of \ weights}{# \ of \ data \ points}\), or in our case \(average \ height=\frac{sum \ of \ heights}{# \ of \ people}\).

(1) The average height of \(\frac{n}{3}\) people is 74.5 inches and the average height of \(\frac{2n}{3}\) people (the res of the people in the group \(n-\frac{n}{3}=\frac{2n}{3}\)) is 70 inches --> \(average \ height=\frac{sum \ of \ heights}{# \ of \ people}=\frac{74.5*\frac{n}{3}+70*\frac{2n}{3}}{n}\) --> \(n\) cancels out --> \(average \ height=74.5*\frac{1}{3}+70*\frac{2}{3}\). Sufficient.

(2) Sum of heights equals to 178 feet 9 inches --> only nominator is given. Not sufficient.

Re: What is the average (arithmetic mean) height of the n people [#permalink]

Show Tags

21 Mar 2010, 11:35

1

This post received KUDOS

nifoui wrote:

What is the average (arithmetic mean) height of the n people in a certain group?

(1) The average height of the n/3 tallest people in the group is 6 feet 2(1/2) inches, and the average height of the rest of the people in the group is 5 feet 10 inches.

(2) The sum of the heightsof the n people is 178 feet 9 inches.

Stmt1: Avg of n/3 people= 6feet 2(1/2) inches = n/3 * 6feet 2(1/2) inches Avg of 2n/3 people = 5feet 10 inches = 2n /3*5feet 10 inches If we add both above quantities and divide it by n we will get the avg since n will cancel out. So, sufficient.

Stmt2: if sum is given to calculate avg we have to divide it by n. But we dont know the value of n so insufficient. Hence A is the answer _________________

Re: What is the average (arithmetic mean) height of the n people [#permalink]

Show Tags

21 Mar 2010, 23:49

1

This post received KUDOS

Socker121314 wrote:

IMO E....from the information provided we don't know what N is.

but if u see statement 1 you can find out avg without knowing n Avg = (n/3 * 6feet 2(1/2) inches + 2n /3*5feet 10 inches ) / n = 1/3 * 6feet 2(1/2) inches + 2 /3*5feet 10 inches we dont need to convert it and calculate but we can find the value. So answer is A _________________

What is the average (arithmetic mean) height of the n people [#permalink]

Show Tags

14 Jul 2010, 13:35

1

This post received KUDOS

6

This post was BOOKMARKED

What is the average (arithmetic mean) height of the n people in a certain group?

(1) The average height of the n/3 tallest people in the group is 6 feet and 2.5 inches and the average height of the rest of the people in the group is 5 feet 10 inches (2) the sum of the heights of the n people is 178 feet 9 inches

Bunel - I need one help. This is not a difficult question and it's easy to see that A is sufficient. However I thought B is suf too because the stimulus says N. Now N could be anything. Is it not sufficient to say avg height = sum of heights (given in the second option)/N - N is mentioned in the stem. Why do we have to concern with the actual value of N?

Official Guide:

In data sufficiency problems that ask for the value of a quantity, the data given in the statements are sufficient only when it is possible to determine exactly one numerical value for the quantity.

(1) The average height of \(\frac{n}{3}\) people is 74.5 inches and the average height of \(\frac{2n}{3}\) people (the res of the people in the group \(n-\frac{n}{3}=\frac{2n}{3}\)) is 70 inches --> \(average \ height=\frac{sum \ of \ heights}{# \ of \ people}=\frac{74.5*\frac{n}{3}+70*\frac{2n}{3}}{n}\) --> \(n\) cancels out --> \(average \ height=74.5*\frac{1}{3}+70*\frac{2}{3}\). Sufficient.

(2) Sum of heights equals to 178 feet 9 inches --> only nominator is given. Not sufficient.

Answer: A.

Hope it helps.

Hi Bunuel, The fact that confused me is the word tallest in statement 1. It says "average height of \(n/3\) [highlight]tallest[/highlight] people in the group is 6 feet 2.5 inches.

Isn't this bit ambiguous? We have no clue how many people to consider in tallest category?

It means that if we order these n people from shortest to tallest and consider \(\frac{n}{3}\) tallest people, then their average height would be 74.5 feet. _________________

Bunel - I need one help. This is not a difficult question and it's easy to see that A is sufficient. However I thought B is suf too because the stimulus says N. Now N could be anything. Is it not sufficient to say avg height = sum of heights (given in the second option)/N - N is mentioned in the stem. Why do we have to concern with the actual value of N?

(1) The average height of \(\frac{n}{3}\) people is 74.5 inches and the average height of \(\frac{2n}{3}\) people (the res of the people in the group \(n-\frac{n}{3}=\frac{2n}{3}\)) is 70 inches --> \(average \ height=\frac{sum \ of \ heights}{# \ of \ people}=\frac{74.5*\frac{n}{3}+70*\frac{2n}{3}}{n}\) --> \(n\) cancels out --> \(average \ height=74.5*\frac{1}{3}+70*\frac{2}{3}\). Sufficient.

(2) Sum of heights equals to 178 feet 9 inches --> only nominator is given. Not sufficient.

Answer: A.

Hope it helps.

Hi Bunuel, The fact that confused me is the word tallest in statement 1. It says "average height of \(n/3\) [highlight]tallest[/highlight] people in the group is 6 feet 2.5 inches.

Isn't this bit ambiguous? We have no clue how many people to consider in tallest category?

Re: What is the average (arithmetic mean) height of the n people [#permalink]

Show Tags

03 Aug 2014, 19:03

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: What is the average (arithmetic mean) height of the n people [#permalink]

Show Tags

04 Oct 2015, 13:28

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: What is the average (arithmetic mean) height of the n people [#permalink]

Show Tags

04 Oct 2015, 13:30

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. _________________

Excellent posts dLo saw your blog too..!! Man .. you have got some writing skills. And Just to make an argument = You had such an amazing resume ; i am glad...

So Much $$$ Business school costs a lot. This is obvious, whether you are a full-ride scholarship student or are paying fully out-of-pocket. Aside from the (constantly rising)...

I barely remember taking decent rest in the last 60 hours. It’s been relentless with submissions, birthday celebration, exams, vacating the flat, meeting people before leaving and of...

Rishabh from Gyan one services, India had a one to one interview with me where I shared my experience at IMD till now. http://www.gyanone.com/blog/life-at-imd-interview-with-imd-mba/ ...