How do I compute the standardized sample mean from this data?

How do I compute the standardized sample mean from this data, in which I have to sample 1000 from an exponential random variable? I don't know how to input such an equation or what function is needed

N = 10000;
a=0; b=1;
x = a+(b-a)*rand([N,1]);
lambda = 1;
Y = -log(x)/lambda;

Answer 1

[KSSV]

N = 10000;
a=0; b=1;
x = a+(b-a)*rand([N,1]);
lambda = 1;
Y = -log(x)/lambda;
Y_std = (Y-mean(Y))/std(Y) ;
mean(Y_std)

ans = -2.3590e-16