A scientist claims that the mean incubation period for swan eggs is less than 40 days. Determine

Question:

A scientist claims that the mean incubation period for swan eggs is less than 40 days.
Determine whether the claim represents the null hypothesis or the alternative hypothesis. If a hypothesis test is performed, how should you interpret a decision that
(a) Rejects the null hypothesis?
(b) Fails to reject the null hypothesis?