I want to do a gene expression simulation in R programming. As a result of measuring the expression of ABC gene in healthy rat brain tissue 100 times with 10 different experimental systems, make a simulation where we obtained 500 results with mean = 9, standard sd = 1 and normal distribution and I want the measurements in each experimental system be equal to each other. How can I do that i do this but it sounds not okey

simu= rnorm(10*100, mean=9, sd= 1) ; length(sim)
xpr_expres= sample( simu , 500 , replace= FALSE)