Can someone help me understand how Std Dev and Mean of a set of numbers change when a number added is:
1. Same as Mean
2. Greater than Mean
3. Less than Mean
Tx for clarifying.
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Change in Std Dev when a new number is added
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crackgmat007
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1. same as mean,
mean is same, Stdev is lower (how much lower will depend on the population size)
2.Greater than mean
mean is greater, stdev will be greater of lower depending on how close the new number is close to mean (ie if the new number X is mean<X<mean+SD the SD will be lower, but that's not always the case, it depends on the total number of samples, the characteristics..etc)
so SD can be lower or higher, it depends
well, that's what I gathered. There maybe perfect explanation about this somewhere on internet
3.Lower than mean
same thing, lower mean, but SD will depend on the characteristic of the sample population
I hope this helps
mean is same, Stdev is lower (how much lower will depend on the population size)
2.Greater than mean
mean is greater, stdev will be greater of lower depending on how close the new number is close to mean (ie if the new number X is mean<X<mean+SD the SD will be lower, but that's not always the case, it depends on the total number of samples, the characteristics..etc)
so SD can be lower or higher, it depends
well, that's what I gathered. There maybe perfect explanation about this somewhere on internet
3.Lower than mean
same thing, lower mean, but SD will depend on the characteristic of the sample population
I hope this helps
