given a sample of 12 values,
50 90 50 60
60 80 50 50
70 40 45 70
and a claimed mean on 48

How would you calculate the 99% confidence interval?
do you use [x - t(n-1)a/2 x (s/sqrt(n)] < u < [x - t(n-1)a/2 x (s/sqrt(n)]
where x is the mean, t(n-1)a/2 is from a table, s is the sample std dev, n=12

Also what hypothesis test would one use to determine if the real average is less than the claimed?