> library(boot)

> aircondit$hours
 [1]   3   5   7  18  43  85  91  98 100 130 230 487

> t.test(aircondit$hours)

	One Sample t-test

data:  aircondit$hours 
t = 2.7483, df = 11, p-value = 0.01895
alternative hypothesis: true mean is not equal to 0 
95 percent confidence interval:
  21.52561 194.64105 
sample estimates:
mean of x 
 108.0833 


> samplemeans = replicate(1000, mean(sample(aircondit$hours, 
    12, replace = T)))

> quantile(samplemeans, c(0.025, 0.975))
     2.5%     97.5% 
 48.08333 193.20000