Answer: 1.303639
Step-by-step explanation:
The t-score for a level of confidence is given by :_
, where df is the degree of freedom and
is the significance level.
Given : Level of significance :
Then , significance level :
Sample size :
Then , the degree of freedom for t-distribution:
Using the normal t-distribution table, we have
Thus, the t-score should be used to find the 80% confidence interval for the population mean =1.303639