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## median question..

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goyalsau GMAT Destroyer!
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Tue Nov 23, 2010 3:20 am
Thephu wrote:
sorry, i just posted in PB forum..

DS question with median .. ??

What is the median number of employee assigned per project for the projects at company z?

1) 25% of the project at company Z have 4 or more employees assigned to each project.

2) 35% of the project at company z have 2 or fewer employee assigned to each project

pls help, many thanks.

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anirudhbhalotia Really wants to Beat The GMAT!
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Tue Dec 21, 2010 6:06 am
Interesting question.

What if the first condition was -

1. 25% of the projects at company Z have 4 or less employees assigned to each project.

So will also include the 2nd. condition by default?

P.S. - I couldn't figure out the range at first. It said 4 or more, so that implies any no. above or equal to 4. Being careless.

Warlock007 Rising GMAT Star
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Sun Jun 26, 2011 12:19 pm
sumanr84 wrote:
skprocks wrote:
The remaining 40% of projects have 3 ppl,why? It can be possible that they have 10ppl.
I understand that the least 25% are <=2
Max 35% are >=4
Then the rest 40% could also be <=2 or >=4 or 3.Am I correct?
25% are <=2 that means it could have 0,1 or 2 number of employees/ project

Max 35% are >=4 that means it could have 4,5,6,......any number(we don't know) per project

rest 40% could also be <=2 or >=4 or 3.Am I correct?
No, Since the range <=2 and >=4 is already covered with above scenario. So, we are left with only one possibility i.e. 3 employee/project.
Hey sumanr84
even better than Stuart

shingik Just gettin' started!
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Sat Aug 06, 2011 9:55 pm
I drew a diagram. That is how question immediately formed in my head. Draw a line to represent your range and divide it into 2. The halfway point is your median.

1)Now on your line mark approximately where, from the left, the 35% marker would be (about a third of the line. Everything this to the left is 2 and below . From this step you do not get anything other than that 1 is INSUFF

2)In accordance with 2 put a marker at around the 75% mark so that you can conclude that the rest of the line past this marker is above 4.

Now look at your median or middle marker. It is clearly between 2 and 4. Since we cannot have fractions of people, anything between 2 and 4 has to be 3. It is also obvious from this that you need both pieces of info to derive your answer. So you answer choice should be C. This solution took me 35 seconds. I am usually much slower but this is the type of problem I am good at.

paulielb39 Just gettin' started!
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Tue Sep 06, 2011 9:25 am
What level is this question?

cktoo Just gettin' started!
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Thu Dec 08, 2011 5:34 pm
Stuart Kovinsky wrote:
You may be confusing median with arithmetic mean.

The median is the middle term of an ordered set. The values of the other terms is irrelevant when calculating the median.

For example:

{2, 2, 2, 2, 3, 3, 3, 3, 3, 4, 4, 4, 4}

and

{2, 2, 2, 2, 3, 3, 3, 3, 3, 100, 1000, 10000, 100000}

both have medians of 3.

* * *

(As a small aside: if there's an odd number of terms, the median is the middle term; if there's an even number of terms, the median is the arithmetic mean of the two middle terms.)
So if the question doesn't specify how many projects there are (even or odd), wouldn't the answer be E, because the median could either be 3 (if odd number of projects) or it could be 3.5 (if even number of projects)??

Sharma_Gaurav Really wants to Beat The GMAT!
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Mon Jan 09, 2012 4:26 pm

scholardream Rising GMAT Star
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Mon Apr 23, 2012 7:41 am
I agree with the odd number such as: 1, 1, 2, 2, 3, 3, 3, 3, 3, 4, 100, 1000, 10000 -> median is 3
But how's about even number such as: 1, 1, 2, 2, 3, 3, 3, 3, 3, 3, 4, 100, 1000, 10000. How it can be 3 ?

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Wed Apr 25, 2012 12:07 am
scholardream wrote:
But how's about even number such as: 1, 1, 2, 2, 3, 3, 3, 3, 3, 3, 4, 100, 1000, 10000. How it can be 3 ?
Hi!

When you have an even number of terms, the median is the average of the two middle terms.

Since there are 14 terms in your set, we want the average of the 7th and 8th terms. Since T7 and T8 are both 3, the average is:

(3+3)/2 = 6/2 = 3

and, accordingly, the median is still 3.

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ronnie1985 GMAT Destroyer!
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Fri Apr 27, 2012 11:44 am
This can be easily solved using diagrammatic approach
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tisrar02 Really wants to Beat The GMAT!
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Tue Jun 26, 2012 9:15 am
I had identified that this can be a typical number line question. I made my numbers equal 100 and thus, the median would be the 50th and 51st number divided by 2. At this point, being a DS question, I dont care about what answer I get, as long as I get an answer that is unique.

1) Dont know aything about the next 75% of employee projects-- Not Suffient
2) Dont know about the remaining 65% of employee projects. Not Sufficient

1+2= We know about the 35% being less that 2 AND the 25% being over 4.

35% have less than 2..... 40% have 3........ 25% have more than 4.--> 3 lands on the 50th and 51st number!!!!!!!

That means 3+3/2= 3.. We got the answer! Jump up for joy and go to the next question!

mp2469 Just gettin' started!
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Fri Jun 29, 2012 10:51 am
Okaaaaay. I undertand the logic used but it still doesn't make sense. At best, we know the median for 40%. We don't know the median number of employees for the other 60% of the company. Median for 25% could 5, 6, 10, 100.

Nanners007 Just gettin' started!
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Tue Aug 14, 2012 8:00 pm
Sorry yet again for re-opening this old thread. What confused me was this: how can we know for sure that the remaining 40% isn't split into a 30/10 or 20/20 percentage with a number other than 3 assigned to each sector? The problem doesn't put restrictions on each percentage by stating specifically that each sector must have a distinct number of employees...this is why I chose E. Can someone please explain why my logic here may be flawed or where I am going wrong with this line of thinking...? Thanks a bunch.

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Stuart Kovinsky GMAT Instructor
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Fri Aug 17, 2012 8:11 pm
Nanners007 wrote:
Sorry yet again for re-opening this old thread. What confused me was this: how can we know for sure that the remaining 40% isn't split into a 30/10 or 20/20 percentage with a number other than 3 assigned to each sector? The problem doesn't put restrictions on each percentage by stating specifically that each sector must have a distinct number of employees...this is why I chose E. Can someone please explain why my logic here may be flawed or where I am going wrong with this line of thinking...? Thanks a bunch.
Hi!

We're told that 25% of projects have 4+ employees and 35% have 2- employees. Since the only number that doesn't fall into "4 or more" and "2 or fewer" is 3, all of the remaining projects must have exactly 3 employees.

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eski Rising GMAT Star
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Tue Sep 18, 2012 12:08 pm
gr8 Q

i thinking making a number line here helps

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