t.test.data<-read.table("C:\\Users\\86167\\Desktop\\2.txt", header=T)

attach(t.test.data)
ratio<-weight/height^2
t.test(ratio)

## 
##  One Sample t-test
## 
## data:  ratio
## t = 12.611, df = 5, p-value = 5.569e-05
## alternative hypothesis: true mean is not equal to 0
## 95 percent confidence interval:
##  18.41734 27.84791
## sample estimates:
## mean of x 
##  23.13262