3)Is range > 2

This topic has expert replies
User avatar
Master | Next Rank: 500 Posts
Posts: 398
Joined: Tue Jul 26, 2011 11:39 pm
Location: India
Thanked: 41 times
Followed by:6 members

by prateek_guy2004 » Sat Sep 03, 2011 12:08 pm
I misread the ques as the median of the numbers is greater than 2 and came to a conclusion that the answer is A...

its a day of making silly mistakes.....

A series of 5 numbers is 3, 4, 5, 5, x, is the range greater than 2?
1> the median of the numbers is greater than the mean

Median> mean

3+4+5+5+x/5

median = 5

Then its sufficient

but if its 6 range will vary.



2> the median is 4

meadian= 4

x has to be less than 3

range not clear

Combining statement 1 and 2...range can be clear

Hence C
Don't look for the incorrect things that you have done rather look for remedies....

https://www.beatthegmat.com/motivation-t90253.html

User avatar
Senior | Next Rank: 100 Posts
Posts: 44
Joined: Sun Aug 21, 2011 1:47 am
Thanked: 3 times

by leumas » Mon Sep 12, 2011 10:40 am
ern5231 wrote:A series of 5 numbers is 3, 4, 5, 5, x, is the range greater than 2?
1> the median of the numbers is greater than the mean
2> the median is 4
What needs to be concluded: Is x<3 to answer if Range >2.

A. Not sufficient
x=0, Mean = 3.2, median = 4, Range >2? Yes
x=2, Mean = 3.8, Median =4, Range >2? Yes
x=3, Mean = 4, Median =4, Range >2? No
x=5, Mean = 4.4, Median =5, Range >2? No
x=6, Mean = 4.6, Median = 5, Range >2? Yes
It satisfies requirement of x<3, but it also satisfies x>5

B. Not Sufficient
So plug in x=2 and x=6
x=2, Median =4, Range>2? Yes
x=6, Median = 5, Range >2? Yes
But, x=3, Median =4, Mean = 4, Range >2? No.

So A&B together shows when x<3, it satisfies all the conditions as below:
1. Range>2
2. Median > Mean
3. Median =4

So Answer is C

I hope this is right way of solving!

User avatar
Legendary Member
Posts: 504
Joined: Tue Apr 19, 2011 1:40 pm
Thanked: 114 times
Followed by:11 members

by knight247 » Mon Sep 12, 2011 2:42 pm
deleted

User avatar
Master | Next Rank: 500 Posts
Posts: 312
Joined: Tue Aug 02, 2011 3:16 pm
Location: New York City
Thanked: 130 times
Followed by:33 members
GMAT Score:780

by gmatboost » Mon Sep 12, 2011 9:55 pm
A series of 5 numbers is 3, 4, 5, 5, x, is the range greater than 2?
1> the median of the numbers is greater than the mean
2> the median is 4
We need to determine if 3 <= x <= 5 (range = 2), or not (range > 2).

You should recognize that:
if x <= 4, the median is 4
if 4 <= x <= 5, the median is x
if x >= 5, the median is 5

Statement 1: Median > Mean
Plugging in is one approach, but many people have done this, so instead I will take the approach of figuring out when this is true.

The median is either 4, 5, or x
The mean is (17 + x)/5 = 3.4 + x/5

So, the mean and median are equal in three places:
3.4 + x/5 = 4
x/5 = 0.6
x = 3

3.4 + x/5 = x
3.4 = 0.8x
x = 3.4/0.8 = 34/8 = 17/4 = 4.25

3.4 + x/5 = 5
x/5 = 1.6
x = 8

So, those are the three boundary points, which create 4 regions
When x < 3, the median is 4 but the mean is smaller: MEDIAN > MEAN
When 3 < x < 4.25, the median is 4 or x, and the mean is slightly bigger: MEDIAN < MEAN (if you're not sure about this region, you can just plug in x = 4, which gives you median = 4, mean = 4.2)
When 4.25 < x < 8, the median is x or 5, and the mean is slightly smaller: MEDIAN > MEAN (if you're not sure about this region, you can just plug in x = 6, which gives you median = 5, mean = 4.6)
When x > 8, the median is 5 but the mean is larger: MEDIAN < MEAN

So, MEDIAN > MEAN means either x < 3 (in which case the range is > 2) OR 4.25 < x < 8 (in which case the range might be 2 or it might be bigger). Insufficient.

Statement 2: Median = 4
This is true whenever x <= 4. So, the range may or may not be > 2. Insufficient.

Combined:
St 1 tells us that x < 3 OR 4.25 < x < 8
St 2 tells us that x <= 4
Combined: x < 3. Range > 2. Sufficient.
Greg Michnikov, Founder of GMAT Boost

GMAT Boost offers 250+ challenging GMAT Math practice questions, each with a thorough video explanation, and 100+ GMAT Math video tips, each 90 seconds or less.
It's a total of 20+ hours of expert instruction for an introductory price of just $10.
View sample questions and tips without signing up, or sign up now for full access.


Also, check out the most useful GMAT Math blog on the internet here.

Master | Next Rank: 500 Posts
Posts: 101
Joined: Thu Aug 25, 2011 9:39 pm

by prashant misra » Fri Sep 16, 2011 10:20 pm
i was able to conclude that the answer cannot be derived from the two statements individually but chose the wrong option E and did not think of combining them.next time ill try to keep this in mind.

User avatar
Senior | Next Rank: 100 Posts
Posts: 53
Joined: Sun Apr 10, 2011 12:15 pm
Thanked: 1 times

by Deependra1 » Tue Nov 08, 2011 2:36 am
Answer: B

User avatar
Master | Next Rank: 500 Posts
Posts: 105
Joined: Sun Jan 25, 2009 6:55 pm
Thanked: 2 times
Followed by:1 members

by bpdulog » Wed Nov 09, 2011 12:34 pm
Fell for trap answer B
NO EXCUSES

"Winston tastes good like a cigarette should."

Senior | Next Rank: 100 Posts
Posts: 97
Joined: Sun Jun 24, 2012 11:23 pm

by Ganesh hatwar » Sun Jul 15, 2012 11:25 pm
ern5231 wrote:A series of 5 numbers is 3, 4, 5, 5, x, is the range greater than 2?
1> the median of the numbers is greater than the mean
2> the median is 4
Nas A

when x = 3 Median = 4 and mean > 4

only if x < 3 median is > mean so ans is A

*Not sure though

Senior | Next Rank: 100 Posts
Posts: 87
Joined: Mon May 07, 2012 7:57 am
Thanked: 1 times

by mparakala » Wed Nov 07, 2012 7:28 am
1) median >mean
x can take diff values
not sufficient

2) x=4,3,2,1
not sufficient

together, yes, range will be greater than 2!

ans: [C]

Master | Next Rank: 500 Posts
Posts: 171
Joined: Tue Jan 08, 2013 7:24 am
Thanked: 1 times

by rajeshsinghgmat » Thu Jan 31, 2013 12:12 am
A in Answer.

3,3,4,5,5 gives Median = Mean = 4.

x,3,4,5,5 where, x < 3 will give Median(4) > Mean

Hence, Range (5-x) > 2

Newbie | Next Rank: 10 Posts
Posts: 9
Joined: Thu Feb 07, 2013 12:39 am

by RajeshP » Thu Feb 07, 2013 1:09 am
OA C.

Junior | Next Rank: 30 Posts
Posts: 14
Joined: Tue Jan 29, 2013 2:26 am
Thanked: 1 times

by vongochao » Wed Feb 20, 2013 6:11 pm
in the string!
Median > mean.
that mean max number + x/2 > mean.

so (5+x)/2> (3+4+5+5+x)/5
...
x>3.
2. median is 4. for this string is sufficient.

so both of them are fine.

Senior | Next Rank: 100 Posts
Posts: 45
Joined: Fri Aug 30, 2013 7:51 pm

by ndqv » Sun Sep 01, 2013 9:23 pm
1) Median > Mean
x=2 => Median = 4, mean = 19/5<4, range = 3>2
x=5 => median = 5, mean = 22/5<5, range = 2

=> 1) is IS

2) Median = 4
=> x<=4
x=2 and x=4 will yield different results in term of range.

=> 2) is IS

Combine 2 stats: 4>mean or 20>x+17 or x<3 => range>2

Choose C

Master | Next Rank: 500 Posts
Posts: 447
Joined: Fri Nov 08, 2013 7:25 am
Thanked: 25 times
Followed by:1 members

by Mathsbuddy » Mon Dec 02, 2013 12:04 am
1)Mean = (17+x)/5 < median

There are 2 ways to maximise the range:

a) x>5,x = 5 + t, median = 5 (where t >= 0)
so (17+5+t)/5 < 5
so t < 3 (this works)

b) x<3,x = 3 - t median = 4 (where t >= 0)
so (17+3-t)/5 < 4
so t > 0 (this works)

Now let's try range = 2, x = median = 4.5:
so (17+4.5)/5 < 4.5
21.5 < 22.5 (this works too)
INSUFFICIENT

2)Median = 4
(17+x)/5 < 4
x < 3 (this works)
However, if 3<x<4 then it will not work.
INSUFFICIENT.

Combined:
As shown above, b) x<3,x = 3 - t median = 4 (where t >= 0)
so (17+3-t)/5 < 4
so t > 0 (SUFFICIENT)

Answer C.

User avatar
Master | Next Rank: 500 Posts
Posts: 164
Joined: Sat Sep 20, 2014 10:26 pm
Thanked: 1 times

by jaspreetsra » Wed Oct 15, 2014 12:15 am
A series of 5 numbers is 3, 4, 5, 5, x, is the range greater than 2?
1> the median of the numbers is greater than the mean
2> the median is 4
My answer is C.
Explanation:
1) Mean = (17+x)/5 and median depends on 'what number is x?' NS
2) Median = 4, it tells x must be on LHS, but it may be 2, 3, or 4. NS
1) & 2) together
If x=2; mean is 3.8 < median 4
If x =3; mean is 4 = median
If x =4; mean is 4.2 >median
Hence, range is greater than 2. And answer is c.