int.g <- function(n) {
  u <- runif(n)
  v <- 6-sqrt(36-35*u)
  int1 <- 5*mean(1/(1+5*u))
  int2 <- 35*mean(1/((1+v)*(12-2*v)))
  return(c(int1,int2,sd(5/(1+5*u))/sqrt(n),sd(35/((1+v)*(12-2*v)))/sqrt(n)))
}

int.g(40)