Find the indicated probability The incomes of trainees at a

Find the indicated probability. The incomes of trainees at a local mill are normally distributed with a mean of $1100 and a standard deviation of $150. What percentage of trainees earn less than $900 a month? 40.82% 35.31% 90.82% 9.18%

Solution

We first get the z score for the critical value. As z = (x - u) / s, then as          
          
x = critical value =    900      
u = mean =    1100      
          
s = standard deviation =    150      
          
Thus,          
          
z = (x - u) / s =    -1.333333333      
          
Thus, using a table/technology, the left tailed area of this is          
          
P(z <   -1.333333333   ) =    0.0918 OR 9.18% [ANSWER]