A random sample of 436 mothers in the United States found that their average age at first birth was 25.9 with a standard deviation of 4.5. A random sample of 364 mothers in France found that their average age at first birth was 28.6 with a standard deviation of 9.5. We will be testing if the mothers give birth to their first birth in the United States are at younger ages than those in France. Required:
Calculate the degrees of freedom for this hypothesis test.