SOLUTION: If X is a normal random variable with standard deviation 3.50, and if the probability that X is more than 12.33 is .1271, then what is the mean of X?

Question 630356: If X is a normal random variable with standard deviation 3.50, and if the probability that X is more than 12.33 is .1271, then what is the mean of X?
Answer by stanbon(75887) (Show Source): You can put this solution on YOUR website!
If X is a normal random variable with standard deviation 3.50, and if the probability that X is more than 12.33 is .1271, then what is the mean of X?
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P(x > 12.33) = 0.1271
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Find the z-value with a right tail of 0.1271
invNorm(1-0.1271) = 1.1402
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Use z = (x-u)/s to find u.
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1.1402 = (12.33-u)/3.50
-u = (1.1402*3.50) - 12.33
-u = -8.3393
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u = 8.3393
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Cheers,
Stan H.
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