In: Statistics and Probability
1. A magazine reported that 10% of American drivers read the newspaper while driving. If 500 drivers are selected at random, find the probability that exactly 50 will admit to reading the newspaper while driving.

Mean ( X ) = n * P = 500 * 0.10 = 50
Standard deviation ( X ) = 
Using Normal Approximation to Binomial
P ( X = 50 ) Using continuity correction
P ( 50 - 0.5 < X < 50 + 0.5 ) = P ( 49.5 < X < 50.5 )
       
P ( 49.5 < X < 50.5 )
         
Standardizing the value
         
          
Z = ( 49.5 - 50 ) /
6.7082         
Z =
-0.07         
Z = ( 50.5 - 50 ) /
6.7082         
Z =
0.07         
P ( -0.07 < Z < 0.07 )
         
P ( 49.5 < X < 50.5 ) = P ( Z < 0.07 ) - P ( Z < -0.07
)          
P ( 49.5 < X < 50.5 ) = 0.5297 -
0.4703         
P ( 49.5 < X < 50.5 ) =
0.0594         
P ( X = 50 ) = 0.0594