Answer:
The endpoints of a t-distribution with 1% beyond them in each tail if the sample has size n=20 is ±2.539
Step-by-step explanation:
Consider the provided information.
It is given that the value of n = 20.
Calculate the degree of freedom as shown below:



It is given that t-distribution with 1% beyond them in each tail.
Therefore the value of α = 0.01
Now use the t distribution table to find the critical value with α = 0.01 and degree of freedom 19.
The critical value with α = 0.01 and df = 19 is ±2.539
Hence, the endpoints of a t-distribution with 1% beyond them in each tail if the sample has size n=20 is ±2.539