When $\bar { X }$ Is the Mean of a Random Sample of Size N

Short Answer

When $\bar { X }$ is the mean of a random sample of size n (n is small) from a normal population with mean $\mu$ , the random variable $T = ( \bar { X } - \mu ) / ( S / \sqrt { n } )$ has a probability distribution called t-distribution with n-1 __________.