function [] = chap_5_prob_28()
% 
% Written by:
% -- 
% John L. Weatherwax                2007-04-02
% 
% email: wax@alum.mit.edu
% 
% Please send comments and especially bug reports to the
% above email address.
% 
%-----

% the mean and std of our binomial distribution:
m = 200*0.12
s = sqrt( 200*0.12*(1-0.12) ) 
n_target = 20-0.5;             % <- note the continuity correction

% approximate this binomial with a normal:
z_target = (n_target-m)/s 

1 - normcdf( z_target )