What critical t value would be needed to construct a 90% confidence interval on a sample of size 22?
1.717
1.323
2.080
1.321
1.721
Use n-1 for degrees of freedom. Check a t-table using that value.
To construct a confidence interval, you need to use the Student's t-distribution. The critical t-value necessary depends on the desired confidence level and the degrees of freedom (df) of the sample.
In this case, you have a sample size of 22, which means the degrees of freedom is 22 - 1 = 21.
To find the critical t-value, you need to determine the value that corresponds to the desired confidence level and degrees of freedom.
A 90% confidence interval means that there is a 90% probability that the true population parameter falls within the interval. The remaining 10% is distributed equally in the two tails of the distribution (5% in each tail).
Looking up the critical t-value for a 90% confidence level with 21 degrees of freedom in a t-distribution table or using a statistical software or calculator, we find that the critical t-value is approximately 1.721.
Therefore, the correct answer is 1.721.