Answer:
Degree of freedom = 19
Step-by-step explanation:
We are given the following information in the question:
Sample size, n = 20
For a t-test hypothesis it was claimed that the population mean is greater than 89 second.
1) df
Df denotes the degree of freedom.
2) Degree of freedom = n - 1
where n is the sample size
Degree of freedom = 20 - 1 = 19