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Standard deviation

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Standard deviation

by lolo » Sat Mar 14, 2009 11:18 am
In a certain corporation, the average salary of all employees is $32,000, with a standard deviation of $8,000. Which of the folowing salaries lies between 1 and 2 standard deviation from the average ?

12,000
17,000
36,000
49,000
52,000

Can anyone please help on that one please ?

As usual, the OA is coming next.
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by DanaJ » Sat Mar 14, 2009 11:23 am
The standard deviation is basically a measure of how far an element of a certain series is from the average of the series. In this case, average = 32 000, and standard deviation is 8 000.
Now, the salaries within 8 000 from 32 000 will be between (32 000 - 8 000) and (32 000 + 8 000) or between 24 000 and 40 000. The only salary to be in this interval will be 36 000.
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by lolo » Sat Mar 14, 2009 11:38 am
Great again DanaJ !
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by avenus » Sat Mar 14, 2009 11:38 am
DanaJ wrote:The standard deviation is basically a measure of how far an element of a certain series is from the average of the series. In this case, average = 32 000, and standard deviation is 8 000.
Now, the salaries within 8 000 from 32 000 will be between (32 000 - 8 000) and (32 000 + 8 000) or between 24 000 and 40 000. The only salary to be in this interval will be 36 000.
The question asks about a salary between 1 and 2 stds from the average, thus in the intervals 16K - 24K or 40K - 48K

17000 would then be the right answer
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by lolo » Sat Mar 14, 2009 11:45 am
OA is B

17,000
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by DanaJ » Sat Mar 14, 2009 2:14 pm
Oops... You guys are right... I read: within one standard deviation from the average.
Since it's between 1 and 2 standard deviations, then you get the following:
1 standard deviation limit: between 24 000 and 40 000.
2 standard deviations limit: between 16 000 and 48 000.

The intervals between the two will be from 16 000 to 24 000 and from 40 000 to 48 000.
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