Assume the sample is a random sample from a distribution tha

Assume the sample is a random sample from a distribution that is reasonably normally distributed and we are doing inference for a sample mean. Find the area in a t-distribution below -1.0 if the sample has size n=20.

Solution

The degree of freedom =n-1=20-1=19

P(t with df=19<-1) =0.1649 (from student t table)