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Mathematics 8 Online
OpenStudy (anonymous):

how do you find how many standard deviations are within a mean?

jimthompson5910 (jim_thompson5910):

is that all the question asks?

OpenStudy (anonymous):

the exact question is within how many standard deviations of the mean is the cost of $50. The standard deviation is 21.5

jimthompson5910 (jim_thompson5910):

what value do they give for the mean?

OpenStudy (anonymous):

91

jimthompson5910 (jim_thompson5910):

first we subtract the mean 91 from the cost of 50 50 - 91 = -41 this negative number tells us we are below the mean

jimthompson5910 (jim_thompson5910):

then we divide the difference by the std deviation -41/21.5 = -1.9069767 which is approximate

jimthompson5910 (jim_thompson5910):

so you are roughly 1.9069767 standard deviations below the mean

jimthompson5910 (jim_thompson5910):

this is using the formula z = (x - mu)/sigma x = raw score mu = mean sigma = standard deviation z = z-score

OpenStudy (anonymous):

Ok thank you that helped a lot.

jimthompson5910 (jim_thompson5910):

you're welcome

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