1. The problem statement, all variables and given/known data Let X1, X2,...,X16 be a random sample of size 16 from N(μ=50, σ2=100) distribution. Find P(Xbar > 50 + .6505(s)) 2. Relevant equations Z= (xbar - μ)/(σ/√n) 3. The attempt at a solution So I know the solution of this problem is given by P( T(15 d.f.) > 2.602 ) but I'm not sure why. I notice that you get the value 2.602 by plugging (50 + .6505(s)) in for xbar in the Z equation. I guess I'm not really sure why we use the T distribution here and how you're supposed to come up with the value 2.602. 15 degrees of freedom makes sense.