QUESTION 2 Suppose you are making a 99 confidence interval f

QUESTION 2 Suppose you are making a 99% confidence interval for with the following information: X = 20, S = 2, n = 30. What is the appropriate t-value?

1. 2.75

2. 2.575

3. 2.7564

4. 2.325

Solution

Note that              

alpha/2 = (1 - confidence level)/2 =    0.005      
df = n - 1 =    29          

Thus, by table/technology,
  
t(alpha/2) = critical t for the confidence interval =    2.756385904 = 2.7564 [ANSWER, OPTION 3]