please check my answer

[nancygaye]

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???

 

[tkhunny]

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.

 

[nancygaye]

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.

 

[galactus]

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?.

 

[nancygaye]

Yes! Thanks!