BREAKING: Target Test Prep releases Brand New 2026 On Demand GMAT prep course

Redeem

Knewton DT

This topic has expert replies
Post new topic Post Reply
Previous Topic Next Topic
User avatar
Legendary Member
Posts: 752
Joined: Sun Sep 12, 2010 2:47 am
Thanked: 20 times
Followed by:10 members
GMAT Score:700

Knewton DT

by prachich1987 » Sun Dec 19, 2010 12:35 am
If the variables A, B, and C take on the values 1, 2, 3, 4, 5, 6, 7, 8, or 9 with the frequencies indicated by the bars above, for which of the frequency distributions is the mean equal to the median?


(A) A only

(B) B only

(C) C only

(D) A and B only your answer

(E) A and C only correct

PLZ NOTE THE FIRST ATTACHMENT IS C, SECOND IS B & THIRD IS A Mark ur answer accordingly
Attachments
A.jpg
B.jpg
C.jpg
Top
Source: — Problem Solving |
User avatar
Legendary Member
Posts: 866
Joined: Mon Aug 02, 2010 6:46 pm
Location: Gwalior, India
Thanked: 31 times

by goyalsau » Sun Dec 19, 2010 12:59 am
According to be B only should be the answer.

What is the OA? I m correct, then i will try to explain. otherwise will be looking forward for the explanation.........
Saurabh Goyal
[email protected]
-------------------------


EveryBody Wants to Win But Nobody wants to prepare for Win.
Top
User avatar
Legendary Member
Posts: 752
Joined: Sun Sep 12, 2010 2:47 am
Thanked: 20 times
Followed by:10 members
GMAT Score:700

by prachich1987 » Sun Dec 19, 2010 1:02 am
goyalsau wrote:According to be B only should be the answer.

What is the OA? I m correct, then i will try to explain. otherwise will be looking forward for the explanation.........
The OA given is E i.e A & C follow the property mean=median
Top
User avatar
Legendary Member
Posts: 543
Joined: Tue Jun 15, 2010 7:01 pm
Thanked: 147 times
Followed by:3 members

by anshumishra » Sun Dec 19, 2010 8:55 am
First of all , how to guess it without solving ?

Check the distributions :

The mean and median would be same in a symmetrical distribution :

A and C are symmetrical (If you place a mirror in the center, the left part will resemble the right part).

However, if you want to confirm Here is how you test it. I am doing it for A and leaving the case for B and C.


A can be represented as :

(1,2,2,3,3,3,4,4,4,4,5,5,5,5,5,6,6,6,6,7,7,7,8,8,9)

Mean = 1*1+2*2+3*3+4*4+5*5+6*4+7*3+8*2+9*1 / (1+2+3+4+5+4+3+2+1) = 125/25 = 5

Median = 5 (which number comes at midpoint ?).

Similarly B can be represented as :

(1,1,1,1,1,1,2,2,2,2,2,2,3,3,3,3,3,3,4,4,4,4,4,4,5,5,5,5,6,6,7,7,8,8,9,9)

and C as :

(1,1,1,1,2,2,2,2,3,3,3,3,3,3,4,4,4,4,4,4,5,5,5,5,6,6,6,6,6,6,7,7,7,7,7,7,8,8,8,8,9,9,9,9)

Thanks
Top
User avatar
Community Manager
Posts: 991
Joined: Thu Sep 23, 2010 6:19 am
Location: Bangalore, India
Thanked: 146 times
Followed by:24 members

by shovan85 » Sun Dec 19, 2010 10:00 am
What Anshu has stated is absolutely correct.

When you see a data in a Graph just draw a line in the exact middle of it and see the symmetry.

If both of the sides are mirror image to each other then Mean = Median
If the problem is Easy Respect it, if the problem is tough Attack it
Top
User avatar
Legendary Member
Posts: 752
Joined: Sun Sep 12, 2010 2:47 am
Thanked: 20 times
Followed by:10 members
GMAT Score:700

by prachich1987 » Sun Dec 19, 2010 10:07 am
shovan85 wrote:What Anshu has stated is absolutely correct.

When you see a data in a Graph just draw a line in the exact middle of it and see the symmetry.

If both of the sides are mirror image to each other then Mean = Median

I agree that for A, mean=median
But for B also mean=median though it is not symmetrical.
For B mean=(6*4+4+2*4)/9=4.Also the median is 4

But for C, though it's symmetrical mean is not equal to median
mean=(4*2+6*2+4*1+6*2+4*2)/4=44/9 whereas median is 4.
Top
User avatar
Legendary Member
Posts: 543
Joined: Tue Jun 15, 2010 7:01 pm
Thanked: 147 times
Followed by:3 members

by anshumishra » Sun Dec 19, 2010 10:20 am
prachich1987 wrote:
shovan85 wrote:What Anshu has stated is absolutely correct.

When you see a data in a Graph just draw a line in the exact middle of it and see the symmetry.

If both of the sides are mirror image to each other then Mean = Median

I agree that for A, mean=median
But for B also mean=median though it is not symmetrical.
For B mean=(6*4+4+2*4)/9=4.Also the median is 4

But for C, though it's symmetrical mean is not equal to median
mean=(4*2+6*2+4*1+6*2+4*2)/4=44/9 whereas median is 4.
prachich1987,

Your set B and C is not right.
As mentioned in my previous post they are :

B = (1,1,1,1,1,1,2,2,2,2,2,2,3,3,3,3,3,3,4,4,4,4,4,4,5,5,5,5,6,6,7,7,8,8,9,9)

C = (1,1,1,1,2,2,2,2,3,3,3,3,3,3,4,4,4,4,4,4,5,5,5,5,6,6,6,6,6,6,7,7,7,7,7,7,8,8,8,8,9,9,9,9)


Let me calculate mean/median for C :


Mean = 1*4+2*4+3*6+4*6+5*4+6*6+7*6+8*4+9*4/(4+4+6+6+4+6+6+4+4) = 220/44 = 5
Median = The middle term , here there are 44 terms, So the 22th term would be the middle one = 5.


I guessed you missed the part where I have identified the three sets A, B and C.

The frequency distribution shows, how many times, 1, 2,...9 have appeared.
So, when I write 1 only a single time, in my set, that means 1 has appeared only one time (check the figure).

Hope, now you would get it.

Thanks
Top
User avatar
Community Manager
Posts: 991
Joined: Thu Sep 23, 2010 6:19 am
Location: Bangalore, India
Thanked: 146 times
Followed by:24 members

by shovan85 » Sun Dec 19, 2010 10:28 am
prachich1987 wrote: I agree that for A, mean=median
But for B also mean=median though it is not symmetrical.
For B mean=(6*4+4+2*4)/9=4.Also the median is 4

But for C, though it's symmetrical mean is not equal to median
mean=(4*2+6*2+4*1+6*2+4*2)/4=44/9 whereas median is 4.
I am showing it for C :)

You agree set :
1,1,1,1,2,2,2,2,3,3,3,3,3,3,4,4,4,4,4,4,5,5,5,5,6,6,6,6,6,6,7,7,7,7,7,7,8,8,8,8,9,9,9,9

If yes then how many data are there in the set? 44 Right!! (Calculate the boxes)

What is the sum of data? 10*4+10*4+10*6+10*6+10*2 = 10*22 = 220 (I have taken 9+1, 8+2, 7+3, 4+6 and 5+5)

What is the mean? 220/44 = 5

What is the median? 5
If the problem is Easy Respect it, if the problem is tough Attack it
Top
User avatar
Legendary Member
Posts: 752
Joined: Sun Sep 12, 2010 2:47 am
Thanked: 20 times
Followed by:10 members
GMAT Score:700

by prachich1987 » Sun Dec 19, 2010 11:20 am
Thanks anushmishra ,shovan
I was making a BIG silly mistake..
Top
User avatar
Legendary Member
Posts: 543
Joined: Tue Jun 15, 2010 7:01 pm
Thanked: 147 times
Followed by:3 members

by anshumishra » Sun Dec 19, 2010 11:22 am
prachich1987 wrote:Thanks anushmishra ,shovan
I was making a BIG silly mistake..
No problem prachich1987,

Glad that you got it ! All of us make mistakes.
Top
Post new topic Post Reply
• Page 1 of 1