Assume that the weights of a male students X is normally dis

Assume that the weights of a male students, X is normally distributed with a mean weight of 160 pounds and standard deviation of 20 pounds. out of 1000 men, how many students weigh more than or exactly 190 pounds?

Solution

We first get the z score for the critical value. As z = (x - u) / s, then as          
          
x = critical value =    190      
u = mean =    160      
          
s = standard deviation =    20      
          
Thus,          
          
z = (x - u) / s =    1.5      
          
Thus, using a table/technology, the right tailed area of this is          
          
P(z >   1.5   ) =    0.066807201

Thus, we expect 0.066807201*1000

= 66.807201 OR AROUND 67 students [ANSWER]