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100 points for $49 worth of Veritas practice GMATs FREE VERITAS PRACTICE GMAT EXAMS Earn 10 Points Per Post Earn 10 Points Per Thanks Earn 10 Points Per Upvote ## Is the standard deviation of the set of measurements x1, x2, ##### This topic has 1 expert reply and 0 member replies ## Is the standard deviation of the set of measurements x1, x2, Is the standard deviation of the set of measurements x1, x2, x3, x4, ..., x20 less than 3 ? (1) The variance for the set of measurements is 4. (2) For each measurement, the difference between the mean and that measurement is 2. What's the best way to determine which statement is sufficient? Can any experts assist? ### GMAT/MBA Expert Legendary Member Joined 14 Jan 2015 Posted: 2667 messages Followed by: 122 members Upvotes: 1153 GMAT Score: 770 ardz24 wrote: Is the standard deviation of the set of measurements x1, x2, x3, x4, ..., x20 less than 3 ? (1) The variance for the set of measurements is 4. (2) For each measurement, the difference between the mean and that measurement is 2. What's the best way to determine which statement is sufficient? Can any experts assist? Statement 1: All you need to know here is that there's a mathematical relationship between the variance and the standard deviation of a set. If you have the variance, you can find the standard deviation. (You may recall from Stat class that when you're computing standard deviation, the last step is to take the square root of the variance. If the variance is 4, the standard deviation is 2.) Sufficient. Statement 2: A standard deviation is, a measure of the distance of the elements in a set from the mean. (Again, from stat class, you may recall that when calculating the standard deviation, you first find the mean, you then find the difference between each element in the set and the mean, before squaring those differences, etc.) If you can find the standard deviation, clearly, you can definitively answer the original question. Sufficient. The answer is D _________________ Veritas Prep | GMAT Instructor Veritas Prep Reviews Save$100 off any live Veritas Prep GMAT Course

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