Q. Find the critical value tc for the confidence level c=0.80 and sample size n=9.tc=□ (Round to the nearest thousandth as needed.)
Calculate Degrees of Freedom: Determine the degrees of freedom for the t-distribution. The degrees of freedom (df) for a sample size n is given by df=n−1. For a sample size of n=9, the degrees of freedom is df=9−1=8.
Identify Upper Tail Area: Identify the area in the upper tail for the given confidence level.The confidence level is c=0.80, which means the area in both tails combined is 1−c=0.20. Since the t-distribution is symmetric, the area in each tail is 0.20/2=0.10.
Find Critical t-Value: Use the t-distribution table to find the critical t-value. For df=8 and an area of 0.10 in the upper tail, we look up the t-distribution table to find the corresponding t-value. According to the table, the critical t-value for df=8 and an upper tail area of 0.10 is approximately 1.397.
Round to Nearest Thousandth: Round the critical t-value to the nearest thousandth.The critical t-value from the table is 1.397, which is already rounded to the nearest thousandth.
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