> data(iris)

> iris[1:5, ]
  Sepal.Length Sepal.Width Petal.Length Petal.Width Species
1          5.1         3.5          1.4         0.2  setosa
2          4.9         3.0          1.4         0.2  setosa
3          4.7         3.2          1.3         0.2  setosa
4          4.6         3.1          1.5         0.2  setosa
5          5.0         3.6          1.4         0.2  setosa

> swsetosa[1:5]
[1] 3.5 3.0 3.2 3.1 3.6

> t.test(swsetosa)

	One Sample t-test

data:  swsetosa 
t = 63.9459, df = 49, p-value < 2.2e-16
alternative hypothesis: true mean is not equal to 0 
95 percent confidence interval:
 3.320271 3.535729 
sample estimates:
mean of x 
    3.428 


> t.test(swsetosa, conf.level = 0.9)

	One Sample t-test

data:  swsetosa 
t = 63.9459, df = 49, p-value < 2.2e-16
alternative hypothesis: true mean is not equal to 0 
90 percent confidence interval:
 3.338124 3.517876 
sample estimates:
mean of x 
    3.428