Suppose that you wish to compare the characteristics of tuberculosis meningitis in patients infected with HIV and those who are not infected. In particular, you would like to determine whether the two populations have the same mean age. A sample of 37 infected patients has mean age of 27.9 years and a standard deviation of 5.6 years; a sample of 19 patients who are not infected has mean age = 38.8 years and standard deviation = 21.7 years.

A. What is your calculated t-test value? (Two decimal places, please.)

B. enter the appropriate degrees of freedom to use.

Note: Use excel and explain why you used a certain method to solve this problem.