% Suppose my cat gets sick one day out of seven. % How likely is she to get sick two days in one week? % Here's a compact but tricky way to solve the problem Ntrials = 10000; % number of trials probsick = 1/7; % prob of being sick on a given day count = 0; % number of weeks with two sick days probsick_vector = probsick*ones(7,1); % auxiliary variable for n = 1:Ntrials; % sum(rand(7,1) < probsick_vector) counts the number of sick % days in a given week. If that sum is 2, increment the count count = count + (sum(rand(7,1) < probsick_vector) == 2); end prob = count/Ntrials; fprintf('Prob of two sick days per week is %f\n', prob);