Easy · Probability & Combinatorics · Numerical · ~3 min · #50
An Even Number of Heads
Real interview · Jane Street
You flip a fair coin 100 times. What is the probability that the total number of heads is even?
Hints · 0 of 1 shown
Worked solution
Give the problem an honest attempt first, then reveal the full explanation.
Reported in interviews
- Jane StreetGlassdoor interview question
Candidate-reported and unverified; the firm may phrase it differently or no longer ask it. The wording here is our own paraphrase, and the solution was written and checked independently of any answers posted at the source.
Related questions
Concepts
SymmetryConditioning on the last step
Relevant for
Quant TraderQuant ResearcherQuant DeveloperDesk Quant