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.1. (a) Yes, they all work. (b) Clearly the last two, as one-liners, win on shortness. The third is slightly shorter. (c) This one really depends on how much experience you've had. If your mind goes blank when you see Boolean operators, then the first one will seem clearest. But the first one takes more thinking about cases to ensure that each of the three branches is giving the correct result. Don't impose one correct answer on this part of the problem; let students say what they think, and have them listen to each other when they differ. (d) I guess this one gives the first two versions a moment in the sun. What (d) really means, I think, is that the first two don't use composition of functions. But that's one of the fundamental ideas of the course, and if students aren't yet happy reading compositions, make sure they practice until they /are/ happy with it. (e) The last one clearly wins. Just consider the name of the function: "greater than or equal to." That's exactly what the fourth version says! (f) Of course there's no wrong answer; whatever each student thinks right now is that student's answer. But you can then raise the question, which would you like to find clearest at the end of the course?3.2. If today is Tuesday, it tells you Mary's is closed; on other days it's open. (Mary Chung's is a Chinese restaurant near MIT with a long history as a hacker favorite. It's known for extra spicy food, and especially for Suan La Chow Show (https://en.wikipedia.org/wiki/Suanla_chaoshou). It is indeed closed Tuesdays.) 3.3 Our solution to 2.5 already uses nested conditionals.

As the lab says, it's okay to use ">" and "<" instead of "≥" and "≤."