pivotal quantities - mathematical statistics

Question

What is a pivotal quantity that can be used to find an exact/nonasymptotic interval for μ when σ is unknown? What distribution does it follow? Make sure that your answer is different from the answers you provide to the other subparts of this question.

Answer 1

Use t = (Xbar - mu) / (s/√n). This follows a t distribution with n-1 degrees of freedom.