For this week's problem set, Q2 & Q3 both propose a hypothesis to test ("that night shift workers have FEWER hours of sleep than non-night shift workers") and ("well-rested...LESS likely to have any colds in the past month") - the language makes it sound like we are only interested in one-sided tests. However, in both cases, it is plausible (though I agree less likely) that the difference could be on either side.
Are we allowed to choose a 2-sided test and explain our reasoning, or should we stick to one-sided tests for the purposes of these questions? I think in 'real life' we would choose the more conservative 2-sided test...