Question 1162936
the critical t-score will be as follows:
with 18 observations, the degrees of freedom = 17
with 9 observations, the degrees of freedom = 8
i used the following table:
<a href = "https://www.sjsu.edu/faculty/gerstman/StatPrimer/t-table.pdf" target = "_blank">https://www.sjsu.edu/faculty/gerstman/StatPrimer/t-table.pdf</a>


at 95% confidence level, the two tail critical t-score will be 2.306 with 8 degrees of freedom and 2.110 with 17 degrees of freedom.


at 99% confidence level, the two tail critical t-score will be 3.355 with 8 degrees of freedom and 2.898 with 17 degrees of freedom.


note that the two tail critical t-score at .05 is the same as the one tail critical t-score at .025 and the two tail critical t-score at .01 is the same as the one tail critical t-score at .005.