I have compiled some review questions for the second midterm for Math 61 (apologies for the poor scan quality). I will go over solutions to this problems in tonight’s review session, which will be from 6 to 8 pm in WGYOUNG CS50. Let me know in the comments below if you have any questions (or if you find anything illegible in the handout).

The sum in Problem 4 is

\[

\sum_{k = 0}^{\lfloor n/2 \rfloor} \pmatrix{n \cr 2 k + 1}

\]

where \(\lfloor n/2 \rfloor\) is \(n/2\) if \(n\) is even and \((n-1)/2\) if \(n\) is odd.