What's the degree of freedom for this question?

Question

"The mean number of English courses taken in a two-year time period by male and female college students is believed to be about the same. An experiment is conducted and data are collected from 29 males and 16 females. The males took an average of four English courses with a standard deviation of 0.9. The females took an average of five English courses with a standard deviation of 1.1. Are the means statistically the same? (Use 𝛼 = 0.05)"

NOTE: If you are using a Student's t-distribution for the problem, including for paired data, you may assume that the underlying population is normally distributed. (In general, you must first prove that assumption, though.)

1. State the distribution to use for the test. (Enter your answer in the form z or t df where df is the degrees of freedom. Answer must be rounded to two decimal places.)

I believe the distribution is the student's t-distribution but I'm not sure what the degree of freedom would be., can someone help me figure it out?? it should be t df

Answer 1

Because the standard deviations are close in value, you can use the formula:

d.f. = n(males) + n(females) - 2 = 29 + 16 - 2 = 43