Question: how to calculate confidence interval using t table?
Answer: Step 2: Subtract the confidence level from 1, then divide by two. Step 3: Look up your answers to step 1 and 2 in the t-distribution table. For 9 degrees of freedom (df) and α = 0.025, my result is 2.262. Step 4: Divide your sample standard deviation by the square root of your sample size.