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nisha.menon294
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ds
This topic has expert replies
Source: Beat The GMAT — Data Sufficiency |
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mbaonmind
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Standard deviation shows how much variation there is from the "average" (mean).
1. A low standard deviation indicates that the data points tend to be very close to the mean,
2. A high standard deviation indicates that the data are spread out over a large range of values.
you need both information to know complete list of integer sets.
IMO C
1. A low standard deviation indicates that the data points tend to be very close to the mean,
2. A high standard deviation indicates that the data are spread out over a large range of values.
you need both information to know complete list of integer sets.
IMO C
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eaakbari
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Stem
T={t1,t2,30,40,50} S={s1,s2,30,40,50}
Mean=40 Mean = 40
Statement one
S={s1,25,30,40,50}, Since we have mean, we can find s1. Therefore we have full set of S but no info about T.
Clearly Insuff
Statement two
T={t1,45,30,40,50}, Since we have mean, we can find t1. Therefore we have full set of T but no info about S.
Clearly Insuff
Combined
We have full set of S and full set of T and their means
variance formula is root(x-mean)^2/n-1
So we can find it
Suff
Hence C
T={t1,t2,30,40,50} S={s1,s2,30,40,50}
Mean=40 Mean = 40
Statement one
S={s1,25,30,40,50}, Since we have mean, we can find s1. Therefore we have full set of S but no info about T.
Clearly Insuff
Statement two
T={t1,45,30,40,50}, Since we have mean, we can find t1. Therefore we have full set of T but no info about S.
Clearly Insuff
Combined
We have full set of S and full set of T and their means
variance formula is root(x-mean)^2/n-1
So we can find it
Suff
Hence C
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gmatmachoman
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My 2 cents here:eaakbari wrote:IMO C
Set s :{ 30,40,50 , X, Y}
Since the avg is 40---then the total sum of 5 integers will be 200.
Set S : {200+X+Y}
For Set T :{200 +X+Y}
Now according to st 1 we can have { 30 ,40, 50, 25,55}
Still we are not sure of Set T. So st 1 alone is insufficient!!
Using st 2 alone wont help much as set T gives {30,40,50,45,35}
Combining both the sts 1 & 2 set 2 has closer standard deviation than set S.
