The price of cell phones manufactured by ahmadi inc is norma

The price of cell phones manufactured by ahmadi inc. is normally distributed with a mean of $100 and a standard deviation of $12 what is the probability that a phone costs more than $115?

Solution

Normal Distribution
Mean ( u ) =100
Standard Deviation ( sd )=12
Normal Distribution = Z= X- u / sd ~ N(0,1)                  
a)
P(X > 115) = (115-100)/12
= 15/12 = 1.25
= P ( Z >1.25) From Standard Normal Table
= 0.1056