set.seed(12345)

milage = c( 162, 200, 271, 302, 393, 508, 539, 629, 706,
            777, 884, 1008, 1101, 1182, 1463, 1603, 1984, 2355, 2880 )

library(boot)

B = 500

res = boot(milage, samplemedian, B)
s = sd(res$t)
print(sprintf('t0= %5.3f; 95%% CI=(%5.3f, %5.3f)', res$t0, res$t0 - 2*s, res$t0 + 2*s))

res = boot(milage, samplemean, B)
s = sd(res$t)
print(sprintf('t0-800= %5.3f; 95%% CI=(%5.3f, %5.3f)', res$t0-800, res$t0-800 - 2*s, res$t0-800 + 2*s))