How to find confidence intervals (T-interval) for means and proving they are significantly different from each other. Is there a way to do this on a graphing calculator? What is the best way to do this? Thank you.

Mean(1): 319.9

Standard Deviation(1): 158

N(1): 6270

Mean(2): 330

Standard Deviation (2): 149

N(2): 1162

p-value: .016

Also, is the confidence level (1-p) making it (1-.016) = .984? Or is the c-level usually just .95?