Students in a class were asked to report the number of pets of their family

# petsfrequency

1 3

2 19

3 16

4 9

47

I figured the frequencies from the data provided but how do you calculate the sample mean and sample standard deviation?

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- Apr 10th 2009, 07:43 PMlaserpet statistics
Students in a class were asked to report the number of pets of their family

__# pets____frequency__

1 3

2 19

3 16

__4 9__

47

I figured the frequencies from the data provided but how do you calculate the sample mean and sample standard deviation? - Apr 10th 2009, 10:40 PMmr fantastic
To calculate sample mean from a frequency table, read The Sample Mean

To calculate sample variance from a frequency table read Learning Resources: Statistics: Power from Data! Variance and standard deviation (go down about half way). - Apr 11th 2009, 11:07 AMlaser
Thank you for the information. If I interpreted it correctly, I believe the mean is 125/47.

1*3+2*19+3*16+4*19=125

mean=125/47

I don't think I got the standard deviation right

$\displaystyle [(1-125/47)^{2}*(3/47)]+[(2-125/47)^{2}*(19/47)]$$\displaystyle +[(3-125/47)^{2}*(16/47)]+[(4-125/47)^{2}*(9/47)]=1624/2209$

1624/2209=0.73517

SD=$\displaystyle \sqrt{0.73517}=$0.85740

Is this correct?