$\DeclareMathOperator{\p}{Pr}$ $\DeclareMathOperator{\P}{Pr}$ $\DeclareMathOperator{\c}{^C}$ $\DeclareMathOperator{\or}{ or}$ $\DeclareMathOperator{\and}{ and}$ $\DeclareMathOperator{\var}{Var}$ $\DeclareMathOperator{\E}{E}$ $\DeclareMathOperator{\std}{Std}$ $\DeclareMathOperator{\Ber}{Bern}$ $\DeclareMathOperator{\Bin}{Bin}$ $\DeclareMathOperator{\Poi}{Poi}$ $\DeclareMathOperator{\Uni}{Uni}$ $\DeclareMathOperator{\Exp}{Exp}$ $\DeclareMathOperator{\N}{N}$ $\DeclareMathOperator{\R}{\mathbb{R}}$ $\newcommand{\d}{\, d}$

CS109 Final
Tuesday, March 17th, 8:30am - 11:30am

Logistics

The CS109 final is a 3-hour, closed book, closed calculator/computer/phone exam. You are, however, allowed to bring 6 pages (front and back) of notes in the exam, formatted in any way you like. Make sure to practice before the exam.

Location and Time

When: Tuesday, March 17th, 8:30am - 11:30am
Location info will be announced a week before the exam.

Coverage

The final will be comprehensive of all the material in the course up to and including class on Wednesday, March 11th, 2026. It will place special emphasis on the content covered on the psets, and will have more material from concepts that were not already covered on the midterm. We will not expect you to be able to perform the math of MLE for neural networks or diffusion.

Answer Format

You are going to be solving probability questions by hand. To that extent we are not interested in numeric answers, but rather in formulaic answers. It is fine for your answers to include summations, products, factorials, exponentials, and combinations, unless the question specifically asks for a numeric quantity or closed form. Where numeric answers are required, the use of fractions is fine. You must show your work. Any explanation you provide of how you obtained your answer can potentially allow us to give you partial credit for a problem. For example, describe the distributions and parameter values you used, where appropriate.

What about the Phi table? If it comes up on the exam, I am not going to make you look up values from a phi table. Instead you can leave your answer in terms of phi (the CDF of the standard normal). For example $\Phi(\frac{3}{4})$ is a fine final answer. This was not the case in the past so you will see questions which ask for a numeric answer in the practice exams.

Practice

We strongly recommend doing multiple practice exams before the real thing. They are great for practicing your pacing and getting a sense for how final exam questions are structured. Note: You should not expect that a TA will have prepared to answer these problems in office hours (there are far too many for them to prep them all). If you ask about one of the problems on the Ed forum or in office hours, please be ready to give the full context, and be aware that the TA might not be able to prioritize them. This is especially true if you ask about them more than a week before the exam.

You can do it!

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