std deviation

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std deviation

by pappueshwar » Wed Mar 14, 2012 6:30 am
The lifetimes of all the batteries produced by a certain company in a year have a distribution that is symmetric about the mean m. If the distribution has a standard deviation of d, what percent of the distribution is greater than m+d?

1) 68 percent of the distribution lies in the interval from m-d to m+d, inclusive.
2) 16 percent of the distribution is less than m-d.

OA IS D
Source: — Data Sufficiency |

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by Jim@StratusPrep » Wed Mar 14, 2012 7:28 am
This is likely not going to come up on the GMAT, as it gets into more statistics than the exam tests. You will, however, have to know this in your stats class year 1 of biz school. Take a look here for the definition: https://en.wikipedia.org/wiki/Standard_deviation
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