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Joined: 18 Feb 2015
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For four days of work, a clerk had daily earnings of $150, $140, $150,
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31 Jul 2016, 11:25
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70% (00:48) correct 30% (00:48) wrong based on 122 sessions
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For four days of work, a clerk had daily earnings of $150, $140, $150, and $150 respectively. In which of the following intervals does the standard deviation of the daily earnings lie? A) Between $140 and $150 B) Between $110 and $140 C) Between $40 and $50 D) Between $10 and $20 E) Between $0 and $10
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Manager
Joined: 15 Mar 2015
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Re: For four days of work, a clerk had daily earnings of $150, $140, $150,
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31 Jul 2016, 11:45
The standard deviation is between 0 and 10. The reason is that none of the numbers in the set is further away from the mean than 10(or rather Abs(140(150*3+140)/4)). I am not fully sure how to calculate the standard deviation(I simply remember that there were some formula for calculating the average of the squared distances from the mean for all items in the set from statistics classes  variation), but I believe this will suffice for any GMAT question related to standard deviation.
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Senior Manager
Joined: 02 Mar 2012
Posts: 334

Re: For four days of work, a clerk had daily earnings of $150, $140, $150,
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01 Aug 2016, 00:20
147.5 is the mean .
so all numbers will lie between SD 010
SD is always across the mean.No need for formula here.Just find the mean and the diff fro the farthest integer(ve or +ve diff)
that will give u the range of SD



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Re: For four days of work, a clerk had daily earnings of $150, $140, $150,
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08 Sep 2017, 10:49
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Re: For four days of work, a clerk had daily earnings of $150, $140, $150, &nbs
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