Easy · Statistics & Statistical Inference · Numerical · ~4 min · #95
At Least 220 Heads in 400 Flips
Real interview · Goldman Sachs, Squarepoint Capital
You flip a fair coin 400 times. Estimate the probability of getting at least 220 heads.
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Worked solution
Give the problem an honest attempt first, then reveal the full explanation.
Reported in interviews
- Goldman SachsGlassdoor interview question
Reported with 55 or more heads in 100 flips.
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.
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