Is that the correct procedure to showing unbiasedness.

#1
I want to modify the following program to show unbiasedness using r

Code:
x <- c(10,12,14,13,10,11,9,15,8,14)
mu=mean(x)
T=0 #the statistic
for(i in 1:210){
 r = sample(x,size=4,replace=F)
 T[i]=mean(r)
}
MSE <- (1/209)*sum(T-mu)^2 #mean square error
MSE