IQ scores are standardized to produce a normal dustribution with mean=100...

Mathematics
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and S.D. of 15
A. IQ more than 140
B. IQ between 120 and 140
C. IQ between 90 and 109
D. IQ less than 55
E.  What is the probability that a person selected at random has an IQ that is more than 3 standard deviations from the mean (Above or below)?

Nov 16th, 2014

z = (140-100)/15 =40/15 = 8/3 =2.67

P(z>2.67) = 0.0038

z=(120-100)/15 = 20/15 = 4/3 =1.33

P(1.33<z<2.67) = 0.0880

z=(90-100)/15 =-10/15 =-0.67

z =(109-100)/15  =9/15 =0.6

P(-0.67<z<0.6)=0.4743

P(z>3) =1-0.9987 =0.0013

P(z< -3) =0.0013

Nov 16th, 2014

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Nov 16th, 2014
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Nov 16th, 2014
Dec 9th, 2016
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