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mastergmat1
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If we are given 3 sets of numbers, 3, 2, 4 0 , 6, 3 and the 22 Sep 2007, 10:35
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If we are given 3 sets of numbers,


3, 2, 4

0 , 6, 3

and the question asks for which one of these have the least standard deviation, how do you compute it ?

The Mean is the same..


Second form of question I run into, the mean is the same of the sets and the range is also the same... Is there an easy way to calculate standard deviation in situations like that?



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beckee529
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If we are given 3 sets of numbers, 3, 2, 4 0 , 6, 3 and the 22 Sep 2007, 10:53
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beatgmat
If we are given 3 sets of numbers,


3, 2, 4

0 , 6, 3

and the question asks for which one of these have the least standard deviation, how do you compute it ?

The Mean is the same..

I think you have to look at all the values to see which set is closest to the mean. So even though both sets have a mean (avg) of 3, you can see that the first set: {3, 2, 4} are all close to 3 while the 2nd set: {0 , 6, 3} 0 and 6 are far away from the mean. Hence, the first set has the least SD. In a case like this, I think that computing the SD is a waste of time (depends on answer choices)

Second form of question I run into, the mean is the same of the sets and the range is also the same... Is there an easy way to calculate standard deviation in situations like that? range just tells us the difference between the smallest value and the biggest value in a set. Usually the smaller the range, the more close the set is to mean so it has the least SD (I could be wrong)
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It is good to remember that SD is simply how far an element in a set is from the mean (average). The closer the values are to the mean, the lower the SD.
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GMATBLACKBELT
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If we are given 3 sets of numbers, 3, 2, 4 0 , 6, 3 and the 22 Sep 2007, 11:01
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beatgmat
If we are given 3 sets of numbers,


3, 2, 4

0 , 6, 3

and the question asks for which one of these have the least standard deviation, how do you compute it ?

The Mean is the same..


Second form of question I run into, the mean is the same of the sets and the range is also the same... Is there an easy way to calculate standard deviation in situations like that?
Show more


Where is teh third set??? Anyway you can do the standard deviation but I don't think that its neccessary here.

Re order the numbers from least to greatest.

2,3,4

0,3,6. All you have to do is see that the spread of the numbers is greater in set 2 than in set 1. So set 1 has the smaller Standard deviation.

If you really wanna know how to calculate the SD (which you will probably never have to).

Find the mean of the set: 2+3+4/3= 3 Subtract mean from all terms in the set:

3-2 =1
3-3=0
3-4=-1. Square the differences

1^2
-1^2

Average the squars. 1+1/2 =1. Take the sqrt of the new average sqrt 1=1.
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If we are given 3 sets of numbers, 3, 2, 4 0 , 6, 3 and the 22 Sep 2007, 11:04
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u can calculate it just by lookin at it..
d mean is 3 in both d case
in 1st 2 n 4 r jus 1 unit away from mean n in 2nd 0 n 6 r 3 units away from mean so in 1st case der is less deviation from mean whereas in 2nd case der is more deviation...



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