# quesito 1.
nrep <- 100000
x <- rnorm(7*nrep,mean=50,sd=10)
x <- matrix(x,nrow=nrep)
y <- apply(x,1,sum)
sum(y>360)/length(y)

# quesito 3.
nrep <- 100000
x <- rnorm(5*nrep,mean=50,sd=10)
x <- matrix(x,nrow=nrep)
y <- apply(x,1,mean)
sum(y<48)/length(y)