SOLUTION: If X is a normal random variable with standard deviation 2.50, and if the probability that X is more than 6.95 is .1271, then what is the mean of x?
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Question 885873: If X is a normal random variable with standard deviation 2.50, and if the probability that X is more than 6.95 is .1271, then what is the mean of x? Answer by rothauserc(4718) (Show Source):
You can put this solution on YOUR website! 0.1271 = 1 - Pr(X<6.95)
Pr(X<6.95) = 1 - 0.1271 = 0.8729
The z-value associated with 0.8729 = 1.14
1.14 = (6.95 - mean) / 2.50
6.95 - mean = 2.85
mean = 6.95 - 2.85 = 4.1
