Create a 95% confidence interval for the mean number of hours spent sleeping per day. Interpret the interval in the context of the problem.

# Make a function for confidence interval
ci95 <- function(x) {
  xbar <- mean(x)
  s <- sd(x)
  n <- length(x)
  se <- s/sqrt(n)
  a <- 0.95
  l <- xbar - qt(a,df=n-1)*se
  u <- xbar + qt(a,df=n-1)*se
  c(lower=l, upper=u)
}

# sleep data
sleep <- c(6.1,6.2,6.7,6.2,6.0,6.1,6.1,6.2,6.0,6.4,6.4,6.4,6.4,6.3,6.3,6.3,6.3,6.2,6.2,6.2,6.2,6.3,6.3,6.3,6.3,6.2,6.2,6.2,6.2,6.2,6.2,6.2