HardStochastic Processes
The Ballot Problem
Jane StreetDE Shaw
In an election, candidate A receives 60 votes and candidate B receives 40. The ballots are counted one at a time in uniformly random order. What is the probability that A is strictly ahead throughout the entire count?
Approach
The answer depends only on the two totals.
(a − b)/(a + b).
Answer
Show the final answer
The answer is 0.2. Sign in free for the full worked solution and to check your own answer.
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