clear;
run=10000; %number of runs. Always do this, instead of having "10000" here and there.
e1 = zeros(run,1);
e2 = zeros(run,1);
e3 = zeros(run,1);

for i = 1:run
    x = 3+randn(5,1);
    e1(i,:) = [0.2 0.2 0.2 0.2 0.2]*x;
    e2(i,:) = [0.2 0.3 0.3 0.1 0.1]*x;
    e3(i,:) = [0.6 0.1 0.1 0.1 0.1]*x;
end

x= 0.5:0.1:5.5; %specify the x-axis.
figure
hist(e1, x)
figure
hist(e2, x)
figure
hist(e3, x)

mean_est = mean([e1 e2 e3]); %mean of the 10000 runs
std_est = std([e1 e2 e3]); %standard deviation