SOLUTION: I need help with this one! IQ scores have a normal distribution with a mean of 100 and a standard deviation of 15. Out of a student body of 1800 students, how many would you expec

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Question 139505: I need help with this one!
IQ scores have a normal distribution with a mean of 100 and a standard deviation of 15. Out of a student body of 1800 students, how many would you expect expect to have an IQ above 109?
My answer is: 1800 - 100 = 1700 / 15 = 113.3333
Answer by stanbon(75887) About Me  (Show Source):
You can put this solution on YOUR website!
IQ scores have a normal distribution with a mean of 100 and a standard deviation of 15. Out of a student body of 1800 students, how many would you expect expect to have an IQ above 109?
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1st: Find the z-score for 109
z(109) = (109-100)/15 = 0.6
2nd: Find the probability above IQ=109.
P(x>109) = P(z>0.6) = 0.2743
3rd: Find that percent of 1800
0.2743*1800 = 493 when rounded down
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Cheers,
Stan H.