Null and Alternative Hypotheses · Exercise 8

Suppose that a recent article stated that the mean time students spend doing homework each week is 2.5 hours. A study was then done to see if the mean time has increased in the new century. A random sample of 26 students. The mean length of time the students spent on homework was 3 hours with a standard deviation of 1.8 hours. Suppose that it is somehow known that the population standard deviation is 1.5. If you were conducting a hypothesis test to determine if the mean length of homework has increased, what would the null and alternative hypotheses be? The distribution of the population is normal.
(a) H_0: ________
(b) H_a: ________

Its source prints no answer for this problem, so there's nothing to check against.

OpenStax, Statistics · §9.1 Null and Alternative Hypotheses · Exercise 8