Construct the indicated confidence interval for the population mean u using the t-distribution. Assume the population is normally distributed. c= 0.99, x 12.2, s=4.0, n 10 (Round to one decimal place...

I did the question help, but I don't clearly understand the d.f. and getting thr tc correctly unless I'm using my graphing calculator wrong

Extracted text: Construct the indicated confidence interval for the population mean u using the t-distribution. Assume the population is normally distributed. c= 0.99, x 12.2, s=4.0, n 10 (Round to one decimal place as needed.)