SOLUTION: Assume the Random Variable X is normally distributed with mean = 50 and the standard deviation = 7. Compute the probability. P(X>40). I am really stumped on these and tried to get

Algebra ->  Probability-and-statistics -> SOLUTION: Assume the Random Variable X is normally distributed with mean = 50 and the standard deviation = 7. Compute the probability. P(X>40). I am really stumped on these and tried to get      Log On


   



Question 762913: Assume the Random Variable X is normally distributed with mean = 50 and the standard deviation = 7. Compute the probability. P(X>40). I am really stumped on these and tried to get the same answer on problems you have on this site and I cant seem to do it.
Answer by rothauserc(4718) About Me  (Show Source):
You can put this solution on YOUR website!
for this problem, we first calculate P(X<40) and then
P(X>40) = 1 - P(X<40)
to calculate P(X<40), we calculate the associated z-value
z-value = (40 - 50) / 7 = -1.43
referring to the negative z table values we find that
P(X<40) = .08 and
P(X>40) = 1 - .08 = .92 or 92%