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Mathematics 15 Online
OpenStudy (anonymous):

What are the mean, variance, and standard deviation of these values? Round to the nearest tenth. 92, 97, 53, 90, 95, 98

OpenStudy (anonymous):

@phi

OpenStudy (amistre64):

the number are few so it shouldnt be to bad to freehand it

OpenStudy (amistre64):

mean is: add em up, and divide by how many there are

OpenStudy (amistre64):

and once you have variance, sd = sqrt(var0

OpenStudy (amistre64):

sqrt(var) ... keep undoing the shift and that 0 slips in

OpenStudy (anonymous):

Okay so add them up and divide it by 6?

OpenStudy (amistre64):

yep, theres 6 data points

OpenStudy (anonymous):

I did and i got 87.5 now i need to find my variance and standard devation

OpenStudy (amistre64):

variance is a process create a new set of data to work with by subtracting the mean from the given data points

OpenStudy (anonymous):

well my variance not my SD

OpenStudy (amistre64):

92-mean, 97-mean, 53-mean, ...

OpenStudy (amistre64):

or mean-53 ... if thats simpler to do by hand. The difference is important here and not the signage

OpenStudy (anonymous):

is my variance 4 or 245.6 ?

OpenStudy (amistre64):

dunno, im not creating a set, and i havent seen yours yet

OpenStudy (anonymous):

Well idk what it is neither

OpenStudy (amistre64):

start by working thru the process subtract the mean (or find the difference) from the data points given

OpenStudy (anonymous):

Okay let me try.

OpenStudy (anonymous):

Iv subtracted , divided , multiply and add and still didnt get either of those answers . ?

OpenStudy (anonymous):

Well im basically stuck between 2 answers because i can't figure out what my variance is ?

OpenStudy (amistre64):

{92, 97, 53, 90, 95, 98} -87.5.......................... ---------------------- {4.5, 9.5, 34.5, 2.5, 7.5, 10.5} square the numbers in this new set {4.5, 9.5, 34.5, 2.5, 7.5, 10.5} ^2 {4.5^2, 9.5^2, 34.5^2, 2.5^2, 7.5^2, 10.5^2} and add em all up again .... 1473.5 and divide by 6 to find the average of the 6 numbers: 245.583 or so

OpenStudy (anonymous):

By looking at that. Thank you very much this helped me a lot. I came across as this as my answer mean = 87.5 variance = 245.6 standard deviation = 15.7

OpenStudy (amistre64):

those look fine to me. assuming this is a population and not a sample of course.

OpenStudy (anonymous):

I hope this is my right answer lol. Thank you so much for your help

OpenStudy (amistre64):

good luck :)

OpenStudy (amistre64):

process is:\[mean=\frac{sum}{\#}\] \[var=\frac{sum~\{(a-mean)^2,(b-mean)^2,(c-mean)^2,...\}}{\#}\]

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