for a population with mean 80 and SD of 10 what is the X val

for a population with mean 80 and SD of 10, what is the X value corresponding to z= -0.50?

79.5, -5, 75 or 85

i got 75 but im not sure if that\'s correct.

Solution

Normal Distribution
Mean ( u ) =80
Standard Deviation ( sd )=10
Normal Distribution = Z = X- u / sd ~ N(0,1)                  
Z = (X-80)/10
-0.50 = (X - 80) / 10
X - 80 = -5
X = 75