Calculate the probability for the following values assuming

Calculate the probability for the following values assuming a normal distribution.

a. u=50, o=300, n=24, Prob(X>75)

Solution

sample mean = 50 Std Dev = 300 ==> Standard Error(s) = std dev/sqrt(n) = 61.2372 Find : P( x > 75 ) z = ( x - u )/s = ( 75 - 50 )/61.2372 = 0.41 P( x > 75) = P( Z > 0.41) = P( Z < -0.41) = 0.3409 _ _ _ _ _ _ _ _ _ (From Z-table) = 34.09%