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Fizzle
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#1
Report Thread starter 14 years ago
#1
Hey guys, i cannot do standard deviation at all.. i keep getting the wrong answer!! can someone help me with this:

Find the standard deviation of the following data:
5,6,8,9,13,15,17,24,29,34,38,42

the answer you should get is 12.5.. thanks!!
ive got my s1 mock on wednesday and im really gona fail at this rate!
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Fizzle
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#2
Report Thread starter 14 years ago
#2
:confused: anyone?
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VCVT17
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#3
Report 14 years ago
#3
the sum of the population is:
5+6+8+9+13+15+17+24+29+34+38+42 = 240
the mean is:
u = 240 / 12 = 20
the difference between the mean and the variables:
15 , 14 , 12 , 11 , 7 , 5 , 3 , -4 , -9 , -14, -18 , -22
the (difference) ^2
225 + 196 + 144 + 121 + 49 + 25 + 9 + 16 + 81 + 196 + 324 + 484 = 1870
the Sigma ^2 = 1870 /12 = 155.833
Take the squared root of it: we have Sigma = sqrt(155.833) = 12.483
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Fizzle
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#4
Report Thread starter 14 years ago
#4
thank u so much!!
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