A cost accountant wished to establish the average amount spent by executives per day on travel and lodging. A random sample of 50 executive expense receipts is taken. The average in the sample was $208, and the standard deviation was $29. The accountant prepares a 95-percent confidence interval, which is given below:

N	Mean StDev SE Mean	95% CI
50	208.00 29.00 4.10	(201.12,214.88)

This distribution was created using a t-critical value. What additional information do we need to show that the t-distribution?