please check my answer

nancygaye

New member
Joined
Jun 29, 2006
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7
Annual incomes are:

$125,000
$128,000
$122,000
$133,000
$140,000

1. What is range? $18,000
2. What is the arithmetic mean income? $129,600
3. Population Variance? 245.992
4. Standard deviation? 4599

Second part:
Annual incomes of others in firm - mean=$129,000/std. deviation 8,612. Compare the means and dispersions of the two firms?

What am I supposed to do? What is an dispersion???
 
I got something different for variance and standard deviation. Check thise again. For starters, 4599^2 = 21,150,801 >> 245,992. Something is wrong, there.

Comparing "dispersion" is only a rough look at the standard deviation. Look at them. Compare them. Make some useful observations.
 
Could you tell me what you got as I obviously don't understand how to figure Population Variance and Standard deviation or tell me how to determine. This is an online class so I'm pretty much on my own.

Thanks.
 
Population variance is:

\(\displaystyle \L\\\frac{\sum(x-{\mu})^{2}}{N}\)

N=number of entries
\(\displaystyle {\mu}\)=mean

\(\displaystyle \L\\\frac{(125000-129600)^{2}+(128000-129600)^{2}+(122000-129600)^{2}+(130000-129600)^{2}+(140000-129600)^{2}}{5}
=50,300,000\)

The square root of this is your standard deviation.

Does this help?.
 
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