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Arithmetic mean

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Arithmetic mean

by selango » Sun Jul 25, 2010 9:11 am
For a certain set of n numbers,where n>1,is the average(arithmetic mean)equal to the median?

1.If the n numbers in the set are listed in increasing order,then the difference between any pair of successive numbers in the set is 2.

2.The Range of n numbers in the set is 2(n-1).

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Source: — Data Sufficiency |
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by outreach » Sun Jul 25, 2010 10:34 am
it is not C.. it should be A

1

if n=3, then numbers are 2,4,6....mean=median
if n=4, then numbers are 2,4,6,8....mean equals median

insuff

2
number of elements in the set not clear
insuff


combined 1 and 2
suff
Last edited by outreach on Sun Jul 25, 2010 11:26 pm, edited 1 time in total.
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by kvcpk » Sun Jul 25, 2010 11:12 am
Answer should be A.

1.If the n numbers in the set are listed in increasing order,then the difference between any pair of successive numbers in the set is 2.

This means that the numbers are equidistant from each other. Hence mean=median
SUFF

Range = 2(n-1)

Assume n=3
2(3-1) =4
1,2,5
Range = 4
mean = 6.6
medain = 2
mean not equal to median

2,4,6
Range = 4
Mean = 4
median = 4

Hence INSUFF

pick A
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by outreach » Sun Jul 25, 2010 11:42 am
@kvcpk
can u explain with an example number..
as per my knowledge median(number arranged in order of magnitude) = middle num(odd number of elements) or sum of 2 middle num(even number of elements)

am i wrong?
kvcpk wrote:Answer should be A.

1.If the n numbers in the set are listed in increasing order,then the difference between any pair of successive numbers in the set is 2.

This means that the numbers are equidistant from each other. Hence mean=median
SUFF

Range = 2(n-1)

Assume n=3
2(3-1) =4
1,2,5
Range = 4
mean = 6.6
medain = 2
mean not equal to median

2,4,6
Range = 4
Mean = 4
median = 4

Hence INSUFF

pick A
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by kvcpk » Sun Jul 25, 2010 11:46 am
outreach wrote:@kvcpk
can u explain with an example number..
as per my knowledge median(number arranged in order of magnitude) = middle num(odd number of elements) or sum of 2 middle num(even number of elements)

am i wrong?
Its not the sum of two middle numbers. It is the average of two middle numbers when n is even.


for 2,4,6
mean = 12/3 = 4
Median = middle number = 4

for 2,4,6,8
mean = 20/4 = 5
median = sum of (4+6)/2 = 5
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by selango » Sun Jul 25, 2010 5:13 pm
OA A
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