s1rout1.m

Industrial Mathematics

% Routine 1.1
p = 1/3;                        % one in three volunteers show up
for n=60:80                     % start with 60 calls
    pk = (1-p)^n;               % this is p(0)
    sum = 0;                    % initialize the sum
  for k=1:19                    % recursively compute p(19)
    pk = (n-k+1)*p*pk/k/(1-p);  % p(k) from p(k-1)
    sum = sum + pk;             % sum terms
   end;                         % summation complete for this n
E(n) = sum;                     % tabulate summations
end;                            % tried up to 80 calls
plot(E)                         % graph falls below .1?