Statistics 251: Introduction to Mathematical Probability (Section 2)

Lecture: MWF 11:30am-12:20pm, on Zoom (link on Canvas).
Textbook: A First Course in Probability by Sheldon Ross (6th, 7th, 8th, 9th, or 10th edition), available online here
Course Information: syllabus and schedule
Instructor: Yi Sun (, office hours 12:20pm-1:30pm Friday on Zoom (link on Canvas)
TAs: Micol Tresoldi (, office hours 12:00pm-1:00pm Sunday on Zoom (link on Canvas); Yi Wang (, office hours 4:30pm-5:30pm Thursday on Zoom (link on Canvas)
Piazza: Get help quickly by posting your questions on Piazza.
Gradescope: Submit all assignments on Gradescope (email me for access).
Website: Access this site at

Overview and prerequisites

This course covers fundamentals and axioms; combinatorial probability; conditional probability and independence; binomial, Poisson, and normal distributions; the law of large numbers and the central limit theorem; and random variables and generating functions.

One of the following courses is a prequisite for this course:

Contact me by email if you have questions about whether this course is appropriate for you.

Course Policies

Gradescope: This course will use Gradescope, an online platform for grading exams and homework. Students registered for the course on the first day of class should have received an email to sign up for Gradescope. If you are enrolled in the course and do not have an account, email me immediately. A few notes about Gradescope:

Lectures: Lectures will be synchronous on Zoom during the scheduled lecture time. There is an expectation that students in this course will be actively engaged while on Zoom.

Homework: There will be weekly written homeworks due Monday. Homeworks are posted here. Homework should be submitted electronically via Gradescope before the start of class. To submit on Gradescope, see this Youtube video or follow the steps below:

  1. Produce a legible .pdf file containing your complete solutions to each problem. This does not mean you must type up your solutions; instead, you may scan your handwritten solutions. Some guidelines for scanning are:
    • Gradescope recommends several free mobile/tablet apps which allow you to turn photos into multi-page PDFs. I also suggest using Dropbox mobile scanning.
    • Be sure to preview your scan and make sure it is legible before uploading to Gradescope.
  2. Upload the .pdf file to Gradescope by the submission deadline (11:30am Monday).
  3. Select the page(s) that contain the solution to each of the assigned problems. Failure to do this step will mean that some or all of your problems will not be graded!
Email me or the TAs if you have trouble with the submission procedure.

Exams: There will be one midterm exam and a cumulative final exam according to the following schedule.

The use of notes, textbooks, or electronic devices will not be allowed during exams. No make-up exams will be offered without a letter from the dean or a doctor’s note. No make-ups are possible for the final exam.

Grading: The final course grade will be determined according to the maximum of the two following computations:

The lowest homework scores will be dropped to accommodate illness and other unforeseen circumstances. Late homework will not be accepted.

Collaboration and Academic Integrity: I encourage you to work together on homework! For written homework, you must write your solutions alone and understand what you write. When submitting your homework, you should cite any sources you used (in print, online, or human) other than the textbook and myself.

Accessibility: The University of Chicago is committed to ensuring equitable access to our academic programs and services. Students with disabilities who have been approved for the use of academic accommodations by Student Disability Services (SDS) and need a reasonable accommodation(s) to participate fully in this course should follow the procedures established by SDS for using accommodations. Timely notifications are required in order to ensure that your accommodations can be implemented. Please meet with me to discuss your access needs in this class after you have completed the SDS procedures for requesting accommodations. Information on the SDS registration process is available here.

Recording: The Recording and Deletion Policies for the current academic year can be found in the Student Manual under Petitions, Audio, and Video Recording on Campus.

COVID-19: Students who have been exposed to or who are experiencing symptoms of COVID-19 should contact UChicago Student Wellness immediately to be tested, and reach out to their area Dean of Students to request accommodations for classes until:



Getting Help

Peer Tutoring: UChicago offers peer tutoring via the Core Tutoring Program. See more information here.

Contact me: Please come to office hours or email me or one of the TAs for help if you are having difficulty with the material.